Journal articles on the topic 'Magnetization direction'
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1
Tajik, F., N. Allameh, A. A. Masoudi, and G. Palasantzas. "Nonlinear actuation of micromechanical Casimir oscillators with topological insulator materials toward chaotic motion: Sensitivity on magnetization and dielectric properties." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 9 (September 2022): 093149. http://dx.doi.org/10.1063/5.0100542.
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We have investigated the dynamical actuation of micro-electromechanical systems under the influence of attractive and repulsive Casimir forces between topological insulator plates as a function of their dielectric function and coating magnetization. The analysis of the Casimir force in the limit of strong and weak magnetization shows that the attractive force, which is produced for plate magnetizations in the same direction, is greater than the repulsive force that is produced for opposite magnetizations. However, both forces remain comparable for intermediate magnetizations. Moreover, for weak magnetization, the attractive force becomes stronger for an increasing dielectric function, while the opposite occurs for the repulsive force. On the other hand, increasing magnetization decreases the influence of the dielectric function on both the repulsive and attractive forces. Furthermore, for conservative systems, bifurcation and phase portrait analysis revealed that increasing magnetization decreases the regime of stable operation for devices with attractive forces, while their operation remains always stable under the presence of repulsive forces. Finally, for non-conservative periodically driven systems, the Melnikov function and Poincaré portrait analysis show that for magnetizations in the same direction leading to strong attractive Casimir forces, chaotic motion toward stiction is highly likely to occur preventing the long-term prediction of actuating dynamics. A remedy for this situation is obtained by the application of any magnetization in opposite directions between the interacting surfaces since the repulsive force makes it possible to prevent stiction.
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Guo, Liang Hui, Rui Gao, and Guo Li Zhang. "Estimating the Magnetization Direction of Sources through Correlation between Reduced-to-Pole Anomaly and Normalized Source Strength." Applied Mechanics and Materials 644-650 (September 2014): 3793–96. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.3793.
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Under the effects of remanent magnetization, total magnetization direction is different from geomagnetic field direction, which makes magnetic data processing and interpretation complexity. In this paper, we present a new approach for estimating the total magnetization direction of sources via cross-correlation between the reduced-to-pole anomaly and the normalized source strength (who is less sensitive to remanent magnetization). The geomagnetic field direction is used to calculated the normalized source strength, while various assumed total magnetization directions are used to calculated the RTP anomalies. The maximum correlation between the RTP anomalies and the normalized corresponds to the estimated total magnetization direction. Test on synthetic data showed that the new approach is simple and effective.
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Buchan, K. L., K. D. Card, and F. W. Chandler. "Multiple ages of Nipissing Diabase intrusion: paleomagnetic evidence from the Englehart area, Ontario." Canadian Journal of Earth Sciences 26, no. 3 (March 1, 1989): 427–45. http://dx.doi.org/10.1139/e89-038.
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Nipissing Diabase sills and baked host sediments of the Coleman Member of the Huronian Supergroup east of Englehart, Ontario, are shown to have a characteristic remanent magnetization direction (called N3) that is steeply up and to the west (D = 268.0°, I = −59.0°, k = 42, α95 = 6.0°). Petrographic study indicates that fresh pyroxene gabbro carries the N3 component at most sill sites. A baked contact test with the Coleman Member suggests that the magnetization is primary. The N3 magnetization direction is unlike either the N1 or N2 magnetization direction reported for Nipissing sills at other localities in the Southern Province. Three distinct ages of Nipissing sill emplacement are proposed. A single Nipissing sill site in the sampling area carries the N1 direction.A northeast-trending diabase dyke crosscuts both the Nipissing sills and Coleman sediments. It carries an N2 direction and has overprinted nearby intrusive and sedimentary rocks (D = 282.0°, I = 61.1°, k = 48, α95 = 5.8°). Several N3 sill sites far from the dyke may also carry a softer N2 overprint. However, the N3 and N2 directions and the direction of the present Earth's magnetic field fall near a great circle, making it difficult to separate the N2 and present-field components in such cases.
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Zhang, Henglei, Dhananjay Ravat, Yára R. Marangoni, Guoxiong Chen, and Xiangyun Hu. "Improved total magnetization direction determination by correlation of the normalized source strength derivative and the reduced-to-pole fields." GEOPHYSICS 83, no. 6 (November 1, 2018): J75—J85. http://dx.doi.org/10.1190/geo2017-0178.1.
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The knowledge of total magnetization (magnitude and direction) makes it easier to interpret magnetic anomalies. We have developed a simple crosscorrelation-based method to determine the total magnetization direction of a magnetic source from the vertical derivative of normalized source strength (dNSS) and the reduced-to-pole (RTP) magnetic fields. For most source types, the spread of the dNSS field (or its half-width) is similar to that of the RTP field computed with the correct total magnetization direction, and, thus, the comparison results in a more meaningful correlation coefficient than other functions used in the literature. We have determined the utility of our method using several compact source types (i.e., sphere, dike, horizontal sheet, vertical and horizontal cylinders, and prism). Moreover, the existing methods for determining the direction can be unstable at low latitudes due to noise amplification. A filter that isolates the main features of the anomaly of interest, when applied to both the fields being correlated, improves the performance of the method. We also implement a stabilizing amplitude threshold filter that made the method stable at low latitudes. Model tests indicate that our method estimates the total magnetization directions accurately for low inclinations of total magnetization and inducing field directions. We applied the method to estimate the total magnetization direction of magnetic anomalies in the north and central part of the Goiás Alkaline Province in central Brazil. The RTP fields from the total magnetization directions derived from our method meet the expectations of anomaly symmetry and centering on the outcrops or the edges of the alkaline intrusive bodies. In addition, we found that the resulting magnetic and gravity models of the Goiás Alkaline intrusives were consistent with the geologic model of inverted conical diatremes.
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Wang, Rongbiao, Jian Tang, Zhiyang Deng, and Yihua Kang. "Motion induced eddy current based testing method for the detection of circumferential defects under circumferential magnetization." International Journal of Applied Electromagnetics and Mechanics 64, no. 1-4 (December 10, 2020): 501–8. http://dx.doi.org/10.3233/jae-209357.
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Magnetic flux leakage (MFL) testing is widely applied in the online detection of steel pipes. Different magnetizing directions are required for the detection of defects in different directions. As the speed of online MFL testing increases, the motion induced eddy current (MIEC) effect becomes significant, and the direction of the MIEC is perpendicular to defects in the same direction as the magnetization. Therefore, the magnetic field signal generated by the MIEC perturbation is analyzed by simulation and compared with MFL signal. It is found that the amplitude of the magnetic field signal generated by the MIEC perturbation increases with the rise of the rotational speed and magnetization. In high rotational speed and strong magnetization, the amplitude of the magnetic field signal caused by MIEC perturbation is greater relative to the amplitude of the MFL signal, providing a possibility for detecting defects that are parallel to the direction of magnetization.
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Shi, Lei, Liang Hui Guo, and Feng Yi Guo. "A New Method of Cross-Correlation by Magnetic Dipole for Estimating Magnetization Direction under the Influence of Remanent Magnetization." Applied Mechanics and Materials 644-650 (September 2014): 3459–62. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.3459.
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Processing and interpretation of magnetic data usually require information of total magnetization direction. However, under the effects of remanent magnetization, total magnetization direction is different from induced magnetization direction, which makes data processing and interpretation complexity. In this paper, we present a new method by cross-correlation of magnetic dipole source for determination of magnetization direction from relatively isolated and approximate equiaxial-shape magnetic total field anomaly. This method calculates cross-correlation coefficient between observed magnetic total field anomaly and theoretical magnetic total field anomaly caused by a magnetic dipole source, by using a set of varying parameters of positions and total magnetization direction of dipole source for trial and error. The corresponding magnetization direction of maximum correlation coefficient is regarded as estimated total magnetization direction. Test on synthetic data indicates that this method reliably and effectively estimates the magnetization direction from relatively isolated and approximate equiaxial-shape magnetic total field anomaly.
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Pilkington, Mark, and Majid Beiki. "Mitigating remanent magnetization effects in magnetic data using the normalized source strength." GEOPHYSICS 78, no. 3 (May 1, 2013): J25—J32. http://dx.doi.org/10.1190/geo2012-0225.1.
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We have developed an approach for the interpretation of magnetic field data that can be used when measured anomalies are affected by significant remanent magnetization components. The method deals with remanent effects by using the normalized source strength (NSS), a quantity calculated from the eigenvectors of the magnetic gradient tensor. The NSS is minimally affected by the direction of remanent magnetization present and compares well with other transformations of the magnetic field that are used for the same purpose. It therefore offers a way of inverting magnetic data containing the effects of remanent magnetizations, particularly when these are unknown and are possibly varying within a given data set. We use a standard 3D inversion algorithm to invert NSS data from an area where varying remanence directions are apparent, resulting in a more reliable image of the subsurface magnetization distribution than possible using the observed magnetic field data directly.
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Dannemiller, Neal, and Yaoguo Li. "A new method for determination of magnetization direction." GEOPHYSICS 71, no. 6 (November 2006): L69—L73. http://dx.doi.org/10.1190/1.2356116.
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The characterization and interpretation of magnetic anomalies rely upon knowledge of the total magnetization direction. Magnetization is usually assumed to consist solely, or primarily, of induced magnetization. The presence of strong remanent magnetization can alter the direction significantly and consequently adversely affect the interpretation, leading to erroneous sizes or shapes of causative bodies. Therefore, it is imperative to have some understanding of the total magnetization direction. We propose a method based upon the correlation between two quantities in magnetic data interpretation: the vertical gradient and the total gradient of the reduced-to-pole (RTP) field. This method is tested on both synthetic and field data sets. The results show that the method is effective in a variety of situations, including those with two-dimensional and three-dimensional dipping bodies and a field example that has a large deviation between the inducing field direction and the total magnetization direction.
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Oliveira, V. C., D. P. Sales, V. C. F. Barbosa, and L. Uieda. "Estimation of the total magnetization direction of approximately spherical bodies." Nonlinear Processes in Geophysics Discussions 1, no. 2 (September 5, 2014): 1465–507. http://dx.doi.org/10.5194/npgd-1-1465-2014.
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Abstract. We have developed a fast total-field anomaly inversion to estimate the magnetization direction of multiple sources with approximately spherical shape and known centres. Our method can be applied to interpret multiple sources with different magnetization directions. It neither requires the prior computation of any transformation like reduction to the pole nor the use of regularly spaced data on a horizontal grid. The method contains flexibility to be implemented as a linear or non-linear inverse problem, which results, respectively, in a least-squares or robust estimate of the components of the magnetization vector of the sources. Applications to synthetic data show the robustness of our method against interfering anomalies and errors in the location of the sources' centre. Besides, we show the feasibility of applying the upward continuation to interpret non-spherical sources. Applications to field data over the Goiás Alkaline Province (GAP), Brazil, show the good performance of our method in estimating geological meaningful magnetization directions. The results obtained for a region of the GAP, near from the alkaline complex of Diorama, suggest the presence of non-outcropping sources marked by strong remanent magnetization with inclination and declination close to -70.35° and -19.81°, respectively. This estimated magnetization direction leads to predominantly positive reduced-to-the-pole anomalies, even for other region of the GAP, in the alkaline complex of Montes Claros de Goiás. These results show that the non-outcropping sources near from the alkaline complex of Diorama have almost the same magnetization direction of that ones in the alkaline complex of Montes Claros de Goiás, strongly suggesting that these sources have emplaced the crust almost within the same geological time interval.
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Lubnina, N. V., and N. A. Tarasov. "Paleomagnetic studies sariolyiski conglomerates of the Onega structure of the Karelian craton: Paleoproterozoic global remagnetization." Moscow University Bulletin. Series 4. Geology, no. 6 (December 28, 2018): 18–28. http://dx.doi.org/10.33623/0579-9406-2018-6-18-28.
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As a result of paleomagnetic studies Sariolian 2,4–2,3 Ga conglomerates of the Onega basin of the Karelian protoctaton, two characteristic components of magnetization have been separated. Mean direction of the medium-temperature component has a heap distribution and coincides with mean direction of the Svecofennian remagnetization within the Karelian protocraton. The directions of high-temperature magnetization components isolated in conglomerates have a significant spread, which indicates the primary nature of this magnetization component. Two clusters of high-temperature components associated not only with the composition of protolites, but also with different conditions of rock transformations, including their fluid saturation, are distinguished.
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Oliveira, V. C., D. P. Sales, V. C. F. Barbosa, and L. Uieda. "Estimation of the total magnetization direction of approximately spherical bodies." Nonlinear Processes in Geophysics 22, no. 2 (April 24, 2015): 215–32. http://dx.doi.org/10.5194/npg-22-215-2015.
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Abstract. We have developed a fast total-field anomaly inversion to estimate the magnetization direction of multiple sources with approximately spherical shapes and known centres. Our method is an overdetermined inverse problem that can be applied to interpret multiple sources with different but homogeneous magnetization directions. It requires neither the prior computation of any transformation-like reduction to the pole nor the use of regularly spaced data on a horizontal grid. The method contains flexibility to be implemented as a linear or non-linear inverse problem, which results, respectively, in a least-squares or robust estimate of the components of the magnetization vector of the sources. Applications to synthetic data show the robustness of our method against interfering anomalies and errors in the location of the sources' centre. Besides, we show the feasibility of applying the upward continuation to interpret non-spherical sources. Applications to field data over the Goiás alkaline province (GAP), Brazil, show the good performance of our method in estimating geologically meaningful magnetization directions. The results obtained for a region of the GAP, near to the alkaline complex of Diorama, suggest the presence of non-outcropping sources marked by strong remanent magnetization with inclination and declination close to −70.35 and −19.81°, respectively. This estimated magnetization direction leads to predominantly positive reduced-to-the-pole anomalies, even for other region of the GAP, in the alkaline complex of Montes Claros de Goiás. These results show that the non-outcropping sources near to the alkaline complex of Diorama have almost the same magnetization direction of those ones in the alkaline complex of Montes Claros de Goiás, strongly suggesting that these sources have been emplaced in the crust within almost the same geological time interval.
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Silveyra, Josefina María, and Juan Manuel Conde Garrido. "On the anhysteretic magnetization of soft magnetic materials." AIP Advances 12, no. 3 (March 1, 2022): 035019. http://dx.doi.org/10.1063/9.0000328.
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Electrical steels are still the materials of choice for large-scale transformers and most electric motors. Yet, they may present a nonhomogeneous magnetic nature which prevents describing accurately their anhysteretic magnetization with the Langevin-Weiss model. Although interpolation and extrapolation methods may be used to model any anhysteretic curve, a simple and physically-based model would be of great value for fundamental and applied research. Inspired in the law of partial volumes for gas mixtures, we proposed a law of partial magnetizations for magnetic mixtures. In a two-component system, the model leads to the double Langevin-Weiss function. We also introduced a graphical method and a fitting approach to analyze and model anhysteretic magnetization curves. A semi-log magnetization derivative plot is central to this end. We validated our strategy through well-motivated examples using published data on soft magnets. The single Langevin-Weiss function provided an accurate description of the magnetization of isotropic and anisotropic magnetically homogeneous materials: a soft ferrite and a nanocrystalline alloy, respectively. For modelling a magnetization transverse to the material’s preferred direction, the key is to allow a negative molecular field constant. The double Langevin-Weiss function was suitable for less homogeneous materials, such as a grain-oriented electrical steel magnetized along the rolling direction and a non-oriented electrical steel. Moreover, a highly-grain-oriented electrical steel magnetized transverse to the rolling direction, which exhibits a constricted hysteresis loop, could be modeled in excellent agreement with data. The key for the latter, has been to allow an antiparallel arrangement of the mean magnetization of both components.
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Mazgaj, Witold, and Adam Warzecha. "Influence of electrical steel sheet textures on their magnetization curves." Archives of Electrical Engineering 62, no. 3 (September 1, 2013): 425–37. http://dx.doi.org/10.2478/aee-2013-0034.
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Abstract The Goss texture is a characteristic feature of grain-oriented transformer steel sheets. Generator sheets, which are produced as non-oriented steel sheets, should have isotropic features. However, measurement results of generator sheets, confirmed by crystallographic studies, indicate that these sheets are characterized by certain, quite significant anisotropy. The first purpose of this paper is to present the influence of textures of generator and transformer steel sheets on their magnetization characteristics. The second aim is to propose a method which takes into account the sheet textures in the calculations of magnetization curves. In calculations of magnetization processes in electrical steel sheets, models in which the plane of a sheet sample is divided into an assumed number of specified directions are used. To each direction a certain hysteresis loop, the so-called direction hysteresis, is assigned. The parameters of these direction hystereses depend, among other things, on the texture type in these steel sheets. This paper discusses the method which calculates the parameters of these direction hystereses taking into account the given sheet texture. The proposed method gives a possibility of determining the magnetization characteristics for any direction of the field intensity changes.
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McKenzie, Blair, Dean Hillan, and Clive Foss. "An improved search for magnetization direction." ASEG Extended Abstracts 2012, no. 1 (December 2012): 1–4. http://dx.doi.org/10.1071/aseg2012ab333.
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Shi, Xiaoqing, Hua Geng, and Shuang Liu. "Magnetization Vector Inversion Based on Amplitude and Gradient Constraints." Remote Sensing 14, no. 21 (October 31, 2022): 5497. http://dx.doi.org/10.3390/rs14215497.
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Magnetization vector inversion has been developed since it can increase inversion accuracy due to the unknown magnetization direction caused by remanence. However, the three components of total magnetizations vector are simultaneously inverted and then synthesized into the magnetization magnitude and direction, which increases the inherent non-uniqueness of the inversion. The positions of the three components of the magnetization vector are originally consistent. If there is a lack of constraints between them during the inversion process, they may be misaligned, resulting in a large deviation between the synthesized vector model and the ground truth. To address this issue and at the same time increase the accuracy of the edges of the inversion models, this paper proposes a magnetization vector inversion scheme with model and its gradients’ constraints by sparse Lp norm functions based on the amplitude of the three components of the magnetization vector instead of a single component to improve the accuracy of the inversion result. To evaluate the inversion accuracy performance, an improved evaluation index is also proposed in this paper, which can better evaluate the accuracy of the shape, position and magnetization amplitude of the inversion model. The proposed inversion method can recover the models with higher accuracy compared with traditional methods, indicated by the inverted model and the evaluation indexes. Simulation results based on the open-source SimPEG software and inversion on actual measured Galinge iron ore deposit (China) data verified the effectiveness and advantages of the proposed method.
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Hidalgo-Gato, Marlon C., Valéria C. F. Barbosa, and Vanderlei C. Oliveira. "Magnetic amplitude inversion for depth-to-basement and apparent magnetization-intensity estimates." GEOPHYSICS 86, no. 1 (January 1, 2021): J1—J11. http://dx.doi.org/10.1190/geo2019-0726.1.
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We have developed an inversion method to recover the depth and the total magnetization intensity of the basement under a sedimentary basin using the amplitude of the magnetic anomaly vector (amplitude data). Because the amplitude data are weakly dependent on the magnetization direction, our method is suitable for interpreting areas with remanent magnetization. Our method assumes constant magnetized basement rocks overlain by nonmagnetic sediments. To overcome the inherent ambiguity of potential field data, we assume knowledge of the average depth of the basement and use it as a constraint to regularize the inversion. A sensitivity analysis with synthetic data shows the weak dependency of the magnetic amplitude inversion on the magnetization direction. Different combinations of magnetization directions recover the interface separating sediments from basement rocks. Test on field data over the Foz do Amazonas Basin, Brazil, recovers the shape of the basement relief without any knowledge about the magnetization intensity and direction. The estimated basement relief reveals a smooth basement framework with basement highs in the central part of the area. In a regional-scale perspective, the deeper and constant estimated basement relief at the northernmost limit of the area may suggest changing in crustal domains from a hyperextended continental crust to homogeneous oceanic crust.
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Liu, Shuang, Xiangyun Hu, Dalian Zhang, Bangshun Wei, Meixia Geng, Boxin Zuo, Henglei Zhang, and Saeed Vatankhah. "The IDQ curve: A tool for evaluating the direction of remanent magnetization from magnetic anomalies." GEOPHYSICS 85, no. 5 (July 28, 2020): J85—J98. http://dx.doi.org/10.1190/geo2019-0545.1.
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Natural remanent magnetization acts as a record of the previous orientations of the earth’s magnetic field, and it is an important feature when studying geologic phenomena. The so-called IDQ curve is used to describe the relationship between the inclination ( I) and declination ( D) of remanent magnetization and the Köenigsberger ratio ( Q). Here, we construct the IDQ curve using data on ground and airborne magnetic anomalies. The curve is devised using modified approaches for estimating the total magnetization direction, e.g., identifying the maximal position of minimal reduced-to-the-pole fields or identifying correlations between total and vertical reduced-to-the-pole field gradients. The method is tested using synthetic data, and the results indicate that the IDQ curve can provide valuable information on the remanent magnetization direction based on available data on the Köenigsberger ratio. Then, the method is used to interpret field data from the Yeshan region in eastern China, where ground anomalies have been produced by igneous rocks, including diorite and basalt, which occur along with magnetite and hematite ore bodies. The IDQ curves for 24 subanomalies are constructed, and these curves indicate two main distribution clusters of remanent magnetization directions corresponding to different structural units of magma intrusion and help identify the lithologies of the magnetic sources in areas covered by Quaternary sediments. The estimated remanent magnetization directions for Cenozoic basalt are consistent with measurements made in paleomagnetism studies. The synthetic and field data indicate that the IDQ curve can be used to efficiently estimate the remanent magnetization direction from a magnetic anomaly, which could help with our understanding of geologic processes in an area.
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Yang, Hongwei, Meng Zhang, and Lianchun Long. "Effect of Crack Defects on Magnetostriction and Magnetic Moment Evolution of Iron Thin Films." Nanomaterials 12, no. 7 (April 6, 2022): 1236. http://dx.doi.org/10.3390/nano12071236.
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Molecular dynamics simulations of body-centered cubic (bcc) iron thin films with crack defects were carried out by adopting methods of EAM (Embedded Atom Method) potential, spin/exchange potential and spin/neel potential. In this article, the effects of the variation of distance between two crack defects and their directions on the magnetostrictive properties of the thin films are studied, and the corresponding microscopic mechanism is also analyzed. The results show that the defects affect the atomic magnetic moment nearby, and the magnetostrictive properties of thin iron films vary with the direction and spacing of the crack defects. If the defect spacing is constant, the iron model with crack perpendicular to the magnetization direction has stronger magnetostriction than that of parallel to the magnetization direction. The variation of the defect spacing has a great influence on the magnetostrictive properties of the iron model with crack direction parallel to magnetization direction, but it has a small effect on another perpendicular situation. The atoms between the defects may move, but if the defect spacing increases to a certain value, then none of the atoms will move.
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Liu, Shuang, Xiangyun Hu, Boxin Zuo, Henglei Zhang, Meixia Geng, Yang Ou, Tao Yang, and Saeed Vatankhah. "Susceptibility and remanent magnetization inversion of magnetic data with a priori information of the Köenigsberger ratio." Geophysical Journal International 221, no. 2 (February 3, 2020): 1090–109. http://dx.doi.org/10.1093/gji/ggaa057.
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SUMMARY Magnetic susceptibility and natural remanent magnetization of rocks are useful parameters to study geological structures and geodynamic processes. Traditional widely used algorithms for the inversion of magnetic data can recover the distribution of the apparent susceptibility or total magnetization intensity, but do not provide information on the remanent magnetization. In this paper, we propose a framework to directly invert for the magnetic susceptibility and the natural remanent magnetization vector using surface or airborne magnetic data, assuming that the Köenigsberger ratio of the rock is known or approximately deducible. The susceptibility and remanence are computed using two different approaches: (1) the susceptibility, intensity, and direction of the remanent magnetization are continuously recovered for each discretized cell and (2) the remanence direction is assumed to be uniform in each subzone and is iteratively computed as discrete values. Both processes are implemented using the preconditioned conjugate gradient algorithm. The method is tested on three synthetic models and one field data set from the Zaohuohexi iron-ore deposit, Qinghai Province, northwest China. The results of the continuous inversion show the trend of the remanent magnetization directions, while the discrete inversion yields more specific values. This inversion framework can determine the source bodies’ geometry and position, and also provide superposed and comprehensive information on the natural remanent magnetization, which may be useful to investigate geological bodies bearing stable primary remanent magnetization.
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O’Handley, R. C., and J. P. Woods. "Static magnetization direction under perpendicular surface anisotropy." Physical Review B 42, no. 10 (October 1, 1990): 6568–73. http://dx.doi.org/10.1103/physrevb.42.6568.
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Liu, Shuang, Xiangyun Hu, Tianyou Liu, Jie Feng, Wenli Gao, and Liquan Qiu. "Magnetization vector imaging for borehole magnetic data based on magnitude magnetic anomaly." GEOPHYSICS 78, no. 6 (November 1, 2013): D429—D444. http://dx.doi.org/10.1190/geo2012-0454.1.
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Remanent magnetization and self-demagnetization change the magnitude and direction of the magnetization vector, which complicates the interpretation of magnetic data. To deal with this problem, we evaluated a method for inverting the distributions of 2D magnetization vector or effective susceptibility using 3C borehole magnetic data. The basis for this method is the fact that 2D magnitude magnetic anomalies are not sensitive to the magnetization direction. We calculated magnitude anomalies from the measured borehole magnetic data in a spatial domain. The vector distributions of magnetization were inverted methodically in two steps. The distributions of magnetization magnitude were initially solved based on magnitude magnetic anomalies using the preconditioned conjugate gradient method. The preconditioner determined by the distances between the cells and the borehole observation points greatly improved the quality of the magnetization magnitude imaging. With the calculated magnetization magnitude, the distributions of magnetization direction were computed by fitting the component anomalies secondly using the conjugate gradient method. The two-step approach made full use of the amplitude and phase anomalies of the borehole magnetic data. We studied the influence of remanence and demagnetization based on the recovered magnetization intensity and direction distributions. Finally, we tested our method using synthetic and real data from scenarios that involved high susceptibility and complicated remanence, and all tests returned favorable results.
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Medeiros, Walter E., and João B. C. Silva. "Simultaneous estimation of total magnetization direction and 3-D spatial orientation." GEOPHYSICS 60, no. 5 (September 1995): 1365–77. http://dx.doi.org/10.1190/1.1443872.
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Magnetic interpretations are usually carried out either by assuming induced magnetization and estimating the model geometry, or by presuming a known source spatial orientation to estimate the total magnetization. We present a 3-D magnetic interpretation method that estimates simultaneously the total magnetization direction and the spatial orientation of the source. It is based on the approximation of the anomaly by the series derived from expanding the magnetic potential into multipoles and retaining source moments up to second order. The moments and linear combinations of moments appearing in the series are then inverted from the magnetic anomaly. The total magnetization is assumed constant in direction but not in magnitude. It is also presumed implicitly that the anomalous distribution of magnetization intensity has nonzero values in a finite‐volume region, is far from the observation points, and presents three othogonal planes of symmetry intersecting at the center of the dipole moment. The method is essentially linear and requires no a priori explicit assumption of a fixed geometry for the sources. The method is particularly suited to interpret compact, isolated or disjoint, but spatially correlated sources. If the source satisfies all assumptions presumed by the method, it is possible to obtain accurate, stable estimates of the total dipole moment vector, the position of the center of dipole moment, and the directions of all three principal axes of symmetry. If the source is not far from the observation plane and/or if the total magnetization direction is not constant, it is still possible to obtain accurate and stable estimates of the direction of the mean total magnetization and the projection, on the observation plane, of the center of dipole moment. The method is applied to magnetic data from the Gulf of Guinea Seamount. The estimated magnetic palaeopole is at 50°48′S and 74°54′E which is in good agreement with estimates published by other authors.
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Harlan, Steve S. "Paleomagnetism of Middle Proterozoic diabase sheets from central Arizona." Canadian Journal of Earth Sciences 30, no. 7 (July 1, 1993): 1415–26. http://dx.doi.org/10.1139/e93-122.
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Paleomagnetic results from 1090 Ma diabase sheets of the southwestern U.S.A. diabase province exposed in central Arizona yield two distinct remanent magnetizations (herein termed ADn and ADr), in accordance with the findings of previous investigations. Magnetization ADn is well-defined and has an in situ mean direction of D = 283.3°, I = 45.1° (k = 17.7, α95 = 8.7°, n = 17 independent observations). A mean pole, after correction of paleomagnetic site means for a net 5° clockwise rotation of the Colorado Plateau and transition zone, is located at 22.7°N, 179.3°E (K = 21.9, A95 = 7.8°). The second magnetization (ADr) gives an in situ mean direction of D = 161.1°, I = −87.5° (k = 22.2, α95 = 19.9°, n = 4 independent observations) with a poorly defined pole at 37.6°N, 247.6°E (K = 6.5, A95 = 38.9°). Rock magnetic and alternating field and thermal demagnetization characteristics indicate the ADn and ADr magnetizations are both carried by low-Ti titanomagnetite. Both magnetizations are interpreted to be primary thermoremanent magnetizations acquired during emplacement and cooling of the diabase sheets at about 1090 – 1100 Ma. Comparison of the ADn pole and published geochronologic data from the Arizona diabase with the well-dated normal polarity poles of the Keweenawan region indicates that mafic magmatism in the southwestern U.S.A. diabase province and in the midcontinent rift was essentially synchronous.
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Roest, Walter R., and Mark Pilkington. "Identifying remanent magnetization effects in magnetic data." GEOPHYSICS 58, no. 5 (May 1993): 653–59. http://dx.doi.org/10.1190/1.1443449.
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Remanent magnetization can have a significant influence on the shape of magnetic anomalies in areas that are generally characterized by induced magnetization. Since modeling of magnetic anomalies is nonunique, additional constraints on the direction of magnetization are useful. A method is proposed here to study the possible contribution of remanent magnetization to a particular anomaly, by comparing two functions that are calculated directly from the observations: (1) the amplitude of the analytic signal, and (2) the horizontal gradient of pseudogravity. From the amplitude and relative position of maxima in these derived quantities, we infer the deviation of the magnetization direction from that of the ambient field. The approach is applied to the magnetic anomaly in the center of the Manicouagan impact structure (Canada). Our results, based only on the magnetic anomaly observations, are in close agreement with constraints on the direction of remanent magnetization from rock samples.
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Reis, André L. A., Vanderlei C. Oliveira Jr., and Valéria C. F. Barbosa. "Generalized positivity constraint on magnetic equivalent layers." GEOPHYSICS 85, no. 6 (November 1, 2020): J99—J110. http://dx.doi.org/10.1190/geo2019-0706.1.
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It is known from the potential theory that a continuous and planar layer of dipoles can exactly reproduce the total-field anomaly produced by arbitrary 3D sources. We have proven the existence of an equivalent layer having an all-positive magnetic-moment distribution for the case in which the magnetization direction of this layer is the same as that of the true sources, regardless of whether the magnetization of the true sources is purely induced or not. By using this generalized positivity constraint, we have developed a new iterative method for estimating the total magnetization direction of 3D magnetic sources based on the equivalent-layer technique. Our method does not impose a priori information about the shape or the depth of the sources, does not require regularly spaced data, and presumes that the sources have a uniform magnetization direction. At each iteration, our method performs two steps. The first step solves a constrained linear inverse problem to estimate a positive magnetic-moment distribution over a discrete equivalent layer of dipoles. We consider that the equivalent sources are located on a plane and have a uniform and fixed magnetization direction. In the second step, we use the estimated magnetic-moment distribution and solve a nonlinear inverse problem for estimating a new magnetization direction for the dipoles. The algorithm stops when the equivalent layer yields a total-field anomaly that fits the observed data. Tests with synthetic data simulating different geologic scenarios show that the final estimated magnetization direction is close to the true one. We apply our method to field data from the Goiás alkaline province, over the Montes Claros complex, in the center of Brazil. The results suggest the presence of intrusions with remarkable remanent magnetization, in agreement with the current literature for this region.
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Ghalehnoee, Mohammad Hossein, and Abdolhamid Ansari. "Compact magnetization vector inversion." Geophysical Journal International 228, no. 1 (August 17, 2021): 1–16. http://dx.doi.org/10.1093/gji/ggab330.
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SUMMARY Magnetization vector inversion (MVI) has attracted considerable attention in recent years since by this inversion both distribution of the magnitude and direction of the magnetization are obtained; therefore, it is easy to distinguish between the magnetic causative bodies especially when magnetic data are affected by different remanent magnetization. In this research, the compact magnetization vector inversion is presented: a 3-D magnetic modelling is proposed from surface data measurements to obtain compact magnetization distribution. The equations are solved in data-space least squares and the algorithm includes a combination of two weights as depth weighting and compactness weighting in the Cartesian system. The re-weighted compactness weighting matrix handles sparsity constraints imposed on the magnitude of magnetization for varying Lp-norms ($0 \le p \le 2$). The low value of the norm leads to more focused or compact inversion, and using a large value of p obtains a smooth model. The method is validated with two synthetic examples, the first is a cube that has significant remanent magnetization and the second consists of two causative cube bodies with significant different magnetization directions at different depths. The case study is the magnetic data of Galinge iron ore deposit (China) that the apparent susceptibility and magnetization directions are reconstructed. The compact model reveals that the results agree with drilling and geological information.
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Ribeiro-Filho, Nelson, Rodrigo Bijani, and Cosme Ponte-Neto. "Improving the crosscorrelation method to estimate the total magnetization direction vector of isolated sources: A space-domain approach for unstable inclination values." GEOPHYSICS 85, no. 4 (June 5, 2020): J59—J70. http://dx.doi.org/10.1190/geo2019-0008.1.
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Knowledge of the total magnetization direction of geologic sources is valuable for interpretation of magnetic anomalies. Although the magnetization direction of causative sources is assumed to be induced by the ambient magnetic field, the presence of remanence should not be neglected. An existing method of correlating total and vertical gradients of the reduced-to-the-pole (RTP) anomaly estimates the total magnetization direction well. However, due to the numerical instability of RTP transformation in the Fourier domain, an assumption should be considered for dealing with inclination values at approximately 0°. We have adopted an extension to the standard crosscorrelation method for estimating the total magnetization direction vector, computing the RTP anomaly by means of the classic equivalent layer technique for low inclination values. Additionally, an ideal number of equivalent sources within the layer is considered for reducing the computational demands. To investigate the relevant aspects of the adopted method, two simple synthetic scenarios are presented. First, a magnetic anomaly produced by a homogeneous and isolated vertical dike is considered. This test illustrates the good performance of the adopted approach, finding the true magnetization direction, even for low inclination values. In the second synthetic test, a long-wavelength component is added to the previous magnetic total-field anomaly. In this case, the method adopted here fails to estimate a reliable magnetization direction vector, showing weak performance for strong interfering magnetic anomalies. On the real data example, the application tests an isolated total-field anomaly of the Carajás Mineral Province, in northern Brazil, where the inclination of the ambient magnetic field is close to zero. The obtained results indicate weak remanence in the estimated total magnetization direction vector, which would never be reached in the standard formulation of the crosscorrelation technique.
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Li, Yaoguo, Sarah E. Shearer, Matthew M. Haney, and Neal Dannemiller. "Comprehensive approaches to 3D inversion of magnetic data affected by remanent magnetization." GEOPHYSICS 75, no. 1 (January 2010): L1—L11. http://dx.doi.org/10.1190/1.3294766.
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Three-dimensional (3D) inversion of magnetic data to recover a distribution of magnetic susceptibility has been successfully used for mineral exploration during the last decade. However, the unknown direction of magnetization has limited the use of this technique when significant remanence is present. We have developed a comprehensive methodology for solving this problem by examining two classes of approaches and have formulated a suite of methods of practical utility. The first class focuses on estimating total magnetization direction and then incorporating the resultant direction into an inversion algorithm that assumes a known direction. The second class focuses on direct inversion of the amplitude of the magnetic anomaly vector. Amplitude data depend weakly upon magnetization direction and are amenable to direct inversion for the magnitude of magnetization vector in 3D subsurface. Two sets of high-resolution aeromagnetic data acquired for diamond exploration in the Canadian Arctic are used to illustrate the methods’ usefulness.
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Lubnina, N. V., and V. S. Zakharov. "Determination of contribution from the metachronous components of magnetization to the Precambrian paleomagnetic of the Karelian craton." Moscow University Bulletin. Series 4. Geology, no. 5 (October 28, 2018): 3–13. http://dx.doi.org/10.33623/0579-9406-2018-5-3-13.
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The secondary (metachronous) component of magnetization isolated in the Precambrian complexes of the Karelian craton have been analyzed. The mean directions of high temperature components (deviations from the true direction) depending on the contribution of secondary magnetization components resulting from uneven-aged tectono-magmatic events. It has been shown that the Precambrian key poles often coincide with the vector sum of the ages of Phanerozoic component of magnetization. The conclusion about the primary/secondary origin of the Precambrian paleomagnetic poles must be set on the basis of the integrated petro-paleomagnetic and isotopic data and geological correlations, not only tests of paleomagnetic reliability.
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Abtahi, Sayyed Mohammad, Laust Börsting Pedersen, Jochen Kamm, and Thomas Kalscheuer. "A new reference model for 3D inversion of airborne magnetic data in hilly terrain — A case study from northern Sweden." GEOPHYSICS 83, no. 1 (January 2018): B1—B12. http://dx.doi.org/10.1190/geo2016-0331.1.
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The inherent nonuniqueness in modeling magnetic data can be partly reduced by adding prior information, either as mathematical constructs or simply as bounds on magnetization obtained from laboratory measurements. If a good prior model can be used as a reference model, then the quality of estimated models through an inverse approach can be greatly improved. But even though data on magnetic properties of rocks might exist, their distribution may often be quite irregular on local and regional scales, so that it is difficult to define representative classes of rock types suitable for constraining geophysical models of magnetization. We have developed a new way of constructing a reference model that varies only laterally and is confined to the part of the terrain that lies above the lowest topography in the area. To obtain this model, several estimated 2D magnetization distributions were constructed by data inversion as a function of the iteration number. Then, a suitable 2D model of the magnetization in the topography was chosen as a starting point for constructing a 3D reference model by modifying it with a vertical decay such that its average source depth was the same for all horizontal positions. The average source depth of the reference model was chosen to satisfy the average source depth obtained from analyzing the radial power spectrum of the area studied. Finally, the measured magnetic data were inverted in three dimensions using the given reference model. For a selected reference model, shallow structures indicated a better overall correlation with large remanent magnetizations measured on rock samples from the area. Throughout the entire model, the direction of magnetization was allowed to vary freely. We found that the Euclidean norm of the estimated model was reduced compared with the case where the magnetization direction was fixed.
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Semyung Wang, D. Youn, H. Moon, and J. Kang. "Topology optimization of electromagnetic systems considering magnetization direction." IEEE Transactions on Magnetics 41, no. 5 (May 2005): 1808–11. http://dx.doi.org/10.1109/tmag.2005.846480.
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Hu, H. N., H. Y. Chen, S. Y. Yu, J. L. Chen, G. H. Wu, F. B. Meng, J. P. Qu, Y. X. Li, H. Zhu, and John Q. Xiao. "Textured Co nanowire arrays with controlled magnetization direction." Journal of Magnetism and Magnetic Materials 295, no. 3 (September 2005): 257–62. http://dx.doi.org/10.1016/j.jmmm.2005.01.010.
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Kamimori, T., K. Takai, and M. Goto. "Variation of easy magnetization direction in Y2Fe17−ySixCδ." Journal of Magnetism and Magnetic Materials 104-107 (February 1992): 1219–20. http://dx.doi.org/10.1016/0304-8853(92)90556-4.
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Miyahara, Hideaki, and Kyyoul Yun. "Two-Dimensional AC Magnetic Properties of Electrical Steel Sheet with Two-Dimensional DC-Biased Magnetization." Materials Science Forum 1034 (June 15, 2021): 141–49. http://dx.doi.org/10.4028/www.scientific.net/msf.1034.141.
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To estimate the magnetic properties with two-dimensional AC-magnetization with two-dimensional DC-biased magnetization, three different grades of non-oriented electrical steel sheets with two-dimensional DC-biased magnetization were prepared. As a result, in the high grade specimen, the difference in the magnetic properties depending on the excitation direction (AC excitation direction is parallel to DC excitation direction) was larger than in the low grade specimen, and the magnetic properties were the best when the excitation direction was the rolling direction. Non-oriented electrical steel sheets have small magnetic anisotropy. High grade non-oriented electrical steel sheets have a large magnetic anisotropy to compare with low grade non-oriented electrical steel sheets. It is thought that magnetic anisotropy increased in the high grade non-oriented electrical steel sheets because the B-H loops under DC-biased magnetization were minor loops. In addition, the increase rate of the H widths and the increase rate of the iron losses depending on the excitation direction were relatively consistent. Since the iron loss is proportional to the area of the B-H loop, it is considered that the iron loss increased at the same rate as the H width of the B-H loop.
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Ueda, Yoshio, Ryuji Kubota, and Jiro Segawa. "Magneto‐gravity response function and its application to the Daito Ridge." GEOPHYSICS 67, no. 1 (January 2002): 110–16. http://dx.doi.org/10.1190/1.1451383.
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A magneto‐gravity response function, which shows a phase relationship between magnetic and gravity anomalies caused by a common source body with a constant density‐to‐magnetization ratio, is derived for determining the magnetization direction of a source body for 2‐D and 3‐D cases. The validity of the method is demonstrated through application to test data and to field anomalies from the Daito Ridge. The Daito Ridge is found to be magnetized in the present main field direction, contrary to shallow inclinations suggested by studies of Deep Sea Drilling Project (DSDP) sediment cores. The strong normal magnetization is ascribed to high magnetic susceptibility and/or viscous remanent magnetization.
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Talantsev, Artem D., Ekaterina I. Kunitsyna, and Roman B. Morgunov. "The effect of Dzyaloshinskii–Moriya interaction on direct and backward transition between magnetic states of Pt/Co/Ir/Co/Pr synthetic ferrimagnet." Image Journal of Advanced Materials and Technologies 6, no. 3 (2021): 167–78. http://dx.doi.org/10.17277/jamt.2021.03.pp.167-178.
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In this paper, we present the study of domain structure accompanying interstate transitions in Pt/Co/Ir/Co/Pr synthetic ferrimagnet (SF) of 1.1 nm thick and 0.6 – 1.0 nm thin ferromagnetic Co layers. Variation in the thickness of the thin layer causes noticeable changes in the domain structure and mechanism of magnetization reversal revealed by MOKE (Magneto-Optical Kerr Effect) technique. Magnetization reversal includes coherent rotation of magnetization of the ferromagnetic layers, generation of magnetic nuclei, spreading of domain walls (DW), and development of areas similar with strip domains, dependently on thickness of the thin layer. Inequivalence of the direct and backward transitions between magnetic states of SF with parallel and antiparallel magnetizations was observed in sample with thin layer thicknesses 0.8 nm and 1.0 nm. Asymmetry of the transition between these states is expressed in difference fluctuation fields and shapes of reversal magnetization nucleus contributing to the correspondent forward and backward transitions. We proposed simple model based on asymmetry of Dzyaloshinskii–Moriya interaction. This model explains competition between nucleation and domain wall propagation due to increase/decrease of the DW energy dependently on direction of the spin rotation into the DW in respect to external field.
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Lelièvre, Peter G., and Douglas W. Oldenburg. "A 3D total magnetization inversion applicable when significant, complicated remanence is present." GEOPHYSICS 74, no. 3 (May 2009): L21—L30. http://dx.doi.org/10.1190/1.3103249.
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Inversion of magnetic data is complicated by the presence of remanent magnetization. To deal with this problem, we invert magnetic data for a three-component subsurface magnetization vector, as opposed to magnetic susceptibility (a scalar). The magnetization vector can be cast in a Cartesian or spherical framework. In the Cartesian formulation, the total magnetization is split into one component parallel and two components perpendicular to the earth’s field. In the spherical formulation, we invert for magnetization amplitude and the dip and azimuth of the magnetization direction. Our inversion schemes contain flexibility to obtain different types of magnetization models and allow for inclusion of geologic information regarding remanence. Allowing a vector magnetization increases the nonuniqueness of the magnetic inverse problem greatly, but additional information (e.g., knowledge of physical properties or geology) incorporated as constraints can improve the results dramatically. Commonly available information results in complicated nonlinear constraints in the Cartesian formulation. However, moving to a spherical formulation results in simple bound constraints at the expense of a now nonlinear objective function. We test our methods using synthetic and real data from scenarios involving complicated remanence (i.e., many magnetized bodies with many magnetization directions). All tests provide favorable results and our methods compare well against those of other authors.
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Dunlop, David J. "Paleomagnetism of Archean rocks from northwestern Ontario: V. Poohbah Lake alkaline complex, Quetico Subprovince." Canadian Journal of Earth Sciences 22, no. 1 (January 1, 1985): 27–38. http://dx.doi.org/10.1139/e85-003.
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The Poohbah Lake alkaline complex is a late synkinematic Kenoran pluton in the Quetico gneiss belt of the western Superior Province. Three units of the complex, porphyritic syenite (PS), malignite (M: a nepheline–clinopyroxene–K-feldspar rock), and hornblende syenite (HS), as well as baked Archean schists near the intrusive contact, have a predominantly reverse-polarity R magnetization with mean direction D = 198° I = −22.5° (k = 62, α95 = 5°, N = 13 sites) and a paleopole at 60°E, 50.5°N. Pyrrhotite and coarse primary magnetite are carriers of the R remanence. PS, M, and biotite pyroxenite (BP) exhibit also a predominantly normal N magnetization carried by fine-grained, probably secondary magnetite. N is systematically steeper than R: its mean direction is D = 359.5° I = +55.5° (k = 28, α95 = 8°, N = 13 sites) with a paleopole at 90°E, 77.5°N. R and N do not record an asymmetric field reversal, since reverse-polarity N vectors and normal-polarity R vectors are occasionally found. R resembles in polarity and direction the natural remanent magnetization (NRM) of the 2630 Ma Matachewan diabase. It is probably the primary NRM of the Poohbah Lake pluton, with an age of about 2650 Ma in approximate agreement with the K/Ar isochron age of 2700 ± 25 Ma. N resembles in polarity and direction NRM's from the 2580 Ma Shelley Lake granite and the late Archean Burchell Lake granite. It is probably a secondary NRM about 2550 Ma in age, as suggested by updated K/Ar mica ages. The characteristic NRM of HS samples and secondary magnetizations in other rock types have poles on the Grenville Track of the polar wander path but there is no evidence for Grenvillian-age events in the area.
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Soares, William Pareschi, and Carlos Alberto Mendonça. "Inversion and magnetization homogeneity testing for 2D magnetic sources." GEOPHYSICS 86, no. 1 (January 1, 2021): J13—J19. http://dx.doi.org/10.1190/geo2019-0389.1.
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Many approaches to magnetic data inversion are based on assumptions that source magnetization is homogeneous in direction and intensity. Such assumptions rarely can be verified with independent geologic information and are usually incorporated without further inquiry in the next steps of data interpretation. The use of magnetization direction invariants, such as the gradient intensity of the total field anomaly (equivalent to the amplitude of the analytical signal [ASA]) and the intensity of the anomalous vector field (IAVF), is effective for modeling sources with strong remanent magnetization, usually with unknown direction. Even in such cases, however, the assumption of uniform magnetization is understood but unchecked when seeking smooth or compact solutions from data inversion. We have developed a procedure to test the assumption of uniform magnetization for 2D sources. For true 2D homogeneous sources, the ratio of ASA to IAVF can be modeled with a binary solution (0 and 1) regardless of the real value of the magnetization. A procedure to provide convergence was applied, and its output solution was submitted to a binary test to verify the uniformity hypothesis. This technique was illustrated with numerical simulations and then used to reinterpret a ground magnetic profile across an intrusive diabase body in sediments of the Paraná Basin, Brazil, revealing the existence of two adjacent bodies that are homogeneous with different magnetization intensities.
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Lee, Jin Yi, and Ji Seong Hwang. "A Study of the Quantitative Nondestructive Evaluation Using the Cross Type Magnetic Source and the Magnetic Camera." Key Engineering Materials 321-323 (October 2006): 1447–50. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.1447.
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The magnetic camera using magnetic lens is proposed to satisfy the demands such as obtaining the distribution of the magnetic flux leakage (DMFL) on the high lift-off, and improving sensitivity. However, DMFL is strongly affected by the magnetization direction. Therefore, the DMFL has low intensity when the crack is not perpendicular to the magnetizing direction. Also, quantitative nondestructive evaluation would be difficult. This paper proposes an improved magnetization method to evaluate a crack quantitatively, regardless of the crack direction. The secondary magnetic source, which is perpendicular to the primary magnetic source, is introduced in the scan type magnetic camera. The intensity of two values of ∂B/∂x (1st differential to the magnetization direction) of the DMFL can be used to evaluate the crack volume. The experimental and the numerical analysis results are considered to verify this phenomenon.
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Guspí, Fernando, and Iván Novara. "Reduction to the pole and transformations of scattered magnetic data using Newtonian equivalent sources." GEOPHYSICS 74, no. 5 (September 2009): L67—L73. http://dx.doi.org/10.1190/1.3170690.
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We have developed an equivalent-source method for performing reduction to the pole and related transforms from magnetic data measured on unevenly spaced stations at different elevations. The equivalent source is composed of points located vertically beneath the measurement stations, and their magnetic properties are chosen in such a way that the reduced-to-the-pole magnetic field generated by them is represented by an inverse-distance Newtonian potential. This function, which attenuates slowly with distance, provides better coverage for discrete data points. The magnetization intensity is determined iteratively until the observed field is fitted within a certain tolerance related to the level of noise; thus, advantages in computer time are gained over the resolution of large systems of equations. In the case of induced magnetization, the iteration converges well for verticalor horizontal inclinations, and results are stable if noise is taken into account properly. However, for a range of intermediate inclinations near 35°, a factor tending to zero makes it necessary to perform the reduction through a two-stage procedure, using an auxiliary magnetization direction, without significantly affecting the speed and stability of the method. The performance of the procedure was tested on a synthetic example based on a field generated on randomly scattered stations by a random set of magnetic dipoles, contaminated with noise, which is reduced to the pole for three different magnetization directions. Results provide a good approximation to the theoretical reduced-to-the-pole field using a one- or a two-stage reduction, showing minor noise artifacts when the direction is nearly horizontal. In a geophysical example with real data, the reduction to the pole was used to correct the estimated magnetization direction that originates an isolated anomaly over Sierra de San Luis, Argentina.
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Zhang, Gong, Kun Wang, Yin Pin Wang, Xue Feng Zhou, and Xian Shuai Chen. "Design and Analysis of a Novel Permanent Magnet Arc Guideway Motor." Applied Mechanics and Materials 373-375 (August 2013): 122–29. http://dx.doi.org/10.4028/www.scientific.net/amm.373-375.122.
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Based on the application drawback of the conventional motor reciprocating within certain angle, a novel permanent magnet arc guideway motor (PMAGM) is put forward which directly converts electrical current into limited angular moment, producing torque through a limited rotation angle of normally much less than ±180°. According to the permanent magnet (PM) magnetization and solenoid coil electrifying modes, five different magnetization orientations and three different electrifying modes are analysed. Results show that electromagnetic force of Y direction magnetized alone the external field force lines is larger than any other magnetization orientations, 40% higher than that of vertical magnetization. X direction electromagnetic force magnetized alone the external field force lines in proposal 3 is 2.5 times that of the vertical magnetization in proposal 2. The electromagnetic force and dynamic response performance of designed PMAGM could be improved effectively and provided with certain practical significance.
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Zhang, Shuo, Lian-Chun Long, Jing-Yi Liu, and Yang Yang. "Effect of defects on magnetostriction and magnetic moment evolution of iron thin films." Acta Physica Sinica 71, no. 1 (2022): 017502. http://dx.doi.org/10.7498/aps.71.20211177.
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Magnetostrictive materials have broad application prospects in sensing, control, energy conversion, and information conversion. The improving of the performances and applications of such materials has become a research hotspot, but defects will inevitably appear in the preparation and use of materials. In this study, the magnetostrictive structure model of iron elemental material with no defect or hole defect or crack defect is established by the molecular dynamics method. The influences of different defects on the magnetostrictive behavior of iron thin films are analyzed, and the mechanism of the influence of defects on the magnetostrictive behavior is depicted from the perspective of atomic magnetic moment. The results show that the films with 60 × 2 × 1 defects in the center are the easiest to reach saturation magnetostriction, and the magnetostriction is the least after reaching saturation, with respect to the films without defects. The films with 10 × 10 × 1 and 2 × 60 × 1 defects in the center require a larger magnetic field to approach to saturation, and the magnetostriction of the film with 2 × 60 × 1 defects in the center reaches a maximum value after saturation. This is because the defects will affect the magnetic moment of the surrounding atoms and make them deflect to the direction parallel to the defects, thus affecting the magnetostriction of the iron thin film. Among them, the hole defects have less influence on the magnetostriction, while the crack defects have stronger influence on the magnetostriction. The direction of the crack also has an effect on the magnetostriction of Fe thin film. When the crack is parallel to the direction of magnetization, the maximum magnetostriction of the film in the direction of magnetization from the initial state to the saturation of magnetization will decrease. When the crack is perpendicular to the direction of magnetization, the maximum magnetostriction of the film in the direction of magnetization from the initial state to the saturation of magnetization will increase. These results suggest that the defects affect the magnetostriction of the model as a whole during magnetization by affecting the initial magnetic moment orientation of the surrounding atoms.
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Chen, R. Y., R. Q. Zhang, L. Y. Liao, X. Z. Chen, Y. J. Zhou, Y. D. Gu, M. S. Saleem, X. F. Zhou, F. Pan, and C. Song. "Magnetic field direction dependent magnetization reversal in synthetic antiferromagnets." Applied Physics Letters 115, no. 13 (September 23, 2019): 132403. http://dx.doi.org/10.1063/1.5118928.
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Valev, Ventsislav K., Alejandro V. Silhanek, Werner Gillijns, Yogesh Jeyaram, Hanna Paddubrouskaya, Alexander Volodin, Claudiu G. Biris, et al. "Plasmons Reveal the Direction of Magnetization in Nickel Nanostructures." ACS Nano 5, no. 1 (December 9, 2010): 91–96. http://dx.doi.org/10.1021/nn102852b.
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Sawai, Y., K. Kindo, L. Zhang, J. C. P. Klaasse, E. Brück, K. H. J. Buschow, F. R. de Boer, C. Lefèvre, and G. Venturini. "Change of easy magnetization direction in TmMn6Sn6−xGax (0.00." Journal of Alloys and Compounds 408-412 (February 2006): 196–99. http://dx.doi.org/10.1016/j.jallcom.2005.04.038.
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Colombo, E., O. Donzelli, G. B. Fratucello, and F. Ronconi. "Static magnetization direction in fcc (111) Fe/Ni multilayers." Journal of Magnetism and Magnetic Materials 104-107 (February 1992): 1857–58. http://dx.doi.org/10.1016/0304-8853(92)91578-h.
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Huang, Ping. "Research on Error Diffusion in Bit Patterned Media." Advanced Materials Research 677 (March 2013): 286–89. http://dx.doi.org/10.4028/www.scientific.net/amr.677.286.
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The presence on any variation in the magnetization direction of an island has a detrimental effect on the ability to recover recorded data.To approve this,Ansys Finite Element Method software has been used to simulate the magnetic field intensity distribution in bit patterned media,from the result, It is seen the magnetization direction variations because of thermal fluctuation can cause errors,But this errors can not diffusion, It is isolated.
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Buchan, K. L., and W. R. A. Baragar. "Paleomagnetism of the komatiitic basalts of the Ottawa Islands, N.W.T." Canadian Journal of Earth Sciences 22, no. 4 (April 1, 1985): 553–66. http://dx.doi.org/10.1139/e85-056.
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The komatiitic basalts of the Ottawa Islands in eastern Hudson Bay are on strike with and believed to form a continuation of similar units of the Cape Smith Belt 150 km to the northeast. Units sampled in the Ottawa Islands all dip gently to the west and hence are not suitable for an internal fold test of their age of magnetization. However, before correcting for the tilt of the lavas, the dominant magnetization direction (D = 207.6°, I = 61.9°, k = 168, α95 = 3.7°) does not differ significantly from the uncorrected magnetization direction reported from the steeply dipping, northwest-facing units at Cape Smith (D = 218°, I = 60°, k = 47, α95 = 4°). This negative fold test suggests that the remanence at both locations was acquired after folding. Comparison with the North American Precambrian apparent polar wander path implies that overprinting is related to the Hudsonian Orogeny.A second stable magnetization directed to the west with a shallow inclination is superimposed on the dominant component at a number of sampling sites. Its direction is poorly defined and no fold test is possible. However, magnetic evidence suggests that this component was probably acquired as an overprint after the dominant magnetization, perhaps during a mild reheating associated with the Elsonian Orogeny.
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Khurshid, Hafsa, Rahana Yoosuf, Bashar Afif Issa, Atta G. Attaelmanan, and George Hadjipanayis. "Tuning Easy Magnetization Direction and Magnetostatic Interactions in High Aspect Ratio Nanowires." Nanomaterials 11, no. 11 (November 12, 2021): 3042. http://dx.doi.org/10.3390/nano11113042.
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Cobalt nanowires have been synthesized by electrochemical deposition using track-etched anodized aluminum oxide (AAO) templates. Nanowires with varying spacing-to-diameter ratios were prepared, and their magnetic properties were investigated. It is found that the nanowires’ easy magnetization direction switches from parallel to perpendicular to the nanowire growth direction when the nanowire’s spacing-to-diameter ratio is reduced below 0.7, or when the nanowires’ packing density is increased above 5%. Upon further reduction in the spacing-to-diameter ratio, nanowires’ magnetic properties exhibit an isotropic behavior. Apart from shape anisotropy, strong dipolar interactions among nanowires facilitate additional uniaxial anisotropy, favoring an easy magnetization direction perpendicular to their growth direction. The magnetic interactions among the nanowires were studied using the standard method of remanence curves. The demagnetization curves and Delta m (Δm) plots showed that the nanowires interact via dipolar interactions that act as an additional uniaxial anisotropy favoring an easy magnetization direction perpendicular to the nanowire growth direction. The broadening of the dipolar component of Δm plots indicate an increase in the switching field distribution with the increase in the nanowires’ diameter. Our findings provide an important insight into the magnetic behavior of cobalt nanowires, meaning that it is crucial to design them according to the specific requirements for the application purposes.