Zeitschriftenartikel: „Remanentní magnetická indukce“

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Li, Yaoguo, Jiajia Sun, Shu-Ling Li und Marcelo Leão-Santos. „A paradigm shift in magnetic data interpretation: Increased value through magnetization inversions“. Leading Edge 40, Nr. 2 (Februar 2021): 89–98. http://dx.doi.org/10.1190/tle40020089.1.

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Magnetic data are sensitive to both the induced magnetization in rock units caused by the present earth's magnetic field and the remanent magnetization acquired by rock units in past geologic time. Susceptibility is a direct indicator of the magnetic mineral content, whereas remanent magnetization carries information about the formation process and subsequent structural movement of geologic units. The ability to recover and use total magnetization, defined as the vectorial sum of the induced and remanent magnetization, therefore enables us to take full advantage of magnetic data. The exploration geophysics community has achieved significant advances in inverting magnetic data affected by remanent magnetization. It is now feasible to invert any magnetic data set for total magnetization. We provide an overview of the state of the art in magnetization inversion and demonstrate the informational value of inverted magnetization through a set of case studies from mineral exploration problems. We focus on the methods that recover either the magnitude of the total magnetization or the total magnetization vector itself.

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Evans, D. M., A. Schilling, Ashok Kumar, D. Sanchez, N. Ortega, R. S. Katiyar, J. F. Scott und J. M. Gregg. „Switching ferroelectric domain configurations using both electric and magnetic fields in Pb(Zr,Ti)O 3 –Pb(Fe,Ta)O 3 single-crystal lamellae“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, Nr. 2009 (28.02.2014): 20120450. http://dx.doi.org/10.1098/rsta.2012.0450.

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Thin single-crystal lamellae cut from Pb(Zr,Ti)O 3 –Pb(Fe,Ta)O 3 ceramic samples have been integrated into simple coplanar capacitor devices. The influence of applied electric and magnetic fields on ferroelectric domain configurations has been mapped, using piezoresponse force microscopy. The extent to which magnetic fields alter the ferroelectric domains was found to be strongly history dependent: after switching had been induced by applying electric fields, the susceptibility of the domains to change under a magnetic field (the effective magnetoelectric coupling parameter) was large. Such large, magnetic field-induced changes resulted in a remanent domain state very similar to the remanent state induced by an electric field. Subsequent magnetic field reversal induced more modest ferroelectric switching.

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Roest, Walter R., und Mark Pilkington. „Identifying remanent magnetization effects in magnetic data“. GEOPHYSICS 58, Nr. 5 (Mai 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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Noh, Kyubo, Ki Ha Lee, Seokmin Oh, Soon Jee Seol und Joongmoo Byun. „Numerical evaluation of active source magnetics as a method for imaging high-resolution near-surface magnetic heterogeneity“. GEOPHYSICS 82, Nr. 5 (01.09.2017): J27—J38. http://dx.doi.org/10.1190/geo2016-0435.1.

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We have evaluated a geophysical method that uses a low-frequency magnetic source to image subsurface magnetic heterogeneity. This active source approach can be used to image magnetic features at higher resolutions than the conventional passive geomagnetic method. Importantly, this frequency-domain active source approach is independent of the effects of remanent magnetization, which complicates the interpretation of geomagnetic data. We carried out forward modeling of frequency-domain electromagnetic (EM) data and we found that, at frequencies of a few hertz, the magnetostatic response due to the induced magnetization dominates the EM induction response. The result suggests that it is possible to make magnetic interpretation of low-frequency EM data without having to consider the conductivity structure and the corresponding EM induction effect. We compare the anomalous magnetic responses with magnetic noise components and find that the proposed active source magnetic (ASM) method has a depth of investigation of approximately 300 m. Free-space field and inductive noise are considered as the most important issues affecting the depth of investigation. We also determine the potential for linear interpretation of magnetic heterogeneity under 0.1 SI by showing that the low-frequency magnetic response can be approximated by a linear magnetic response. In our synthetic experiments, inversion of the ASM data shows a marked enhancement in resolution, with no effect of the remanent magnetization, in contrast to geomagnetic inversion. These results show that the ASM method is a useful geophysical tool, especially when high-resolution imaging of magnetic susceptibility is required or where strong remanent magnetization complicates the magnetic interpretation.

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Liu, Shuang, Maurizio Fedi, Xiangyun Hu, Jamaledin Baniamerian, Bangshun Wei, Dalian Zhang und Rixiang Zhu. „Extracting Induced and Remanent Magnetizations From Magnetic Data Modeling“. Journal of Geophysical Research: Solid Earth 123, Nr. 11 (November 2018): 9290–309. http://dx.doi.org/10.1029/2017jb015364.

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Elllis, Robert G., Barrry de Wet und Ian N. Macleod. „Inversion of Magnetic Data from Remanent and Induced Sources“. ASEG Extended Abstracts 2012, Nr. 1 (Dezember 2012): 1–4. http://dx.doi.org/10.1071/aseg2012ab117.

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Yang, Tao, Jintian Gao, Zuowen Gu, Baatarkhuu Dagva und Batsaikhan Tserenpil. „Petrophysical Properties (Density and Magnetization) of Rocks from the Suhbaatar-Ulaanbaatar-Dalandzadgad Geophysical Profile in Mongolia and Their Implications“. Scientific World Journal 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/791918.

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Petrophysical properties of 585 rock samples from the Suhbaatar-Ulaanbaatar-Dalandzadgad geophysical profile in Mongolia are presented. Based on the rock classifications and tectonic units, petrophysical parameters (bulk density, magnetic susceptibility, intensity of natural remanent magnetization, and Köenigsberger ratio) of these rocks are summarized. Results indicate that (1) significant density contrast of different rocks would result in variable gravity anomalies along the profile; (2) magnetic susceptibility and natural remanent magnetization of all rocks are variable, covering 5-6 orders of magnitude, which would make a variable induced magnetization and further links to complex magnetic anomalies in ground surface; (3) the distribution of rocks with different lithologies controls the pattern of lithospheric magnetic anomaly along the profile. The petrophysical database thus provides not only one of the keys to understand the geological history and structure of the profile, but also essential information for analysis and interpretation of the geophysical (e.g., magnetic and gravity) survey data.

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Beard, L. P., J. Norton und J. R. Sheehan. „Lightning-Induced Remanent Magnetic Anomalies in Low-Altitude Aeromagnetic Data“. Journal of Environmental & Engineering Geophysics 14, Nr. 4 (01.12.2009): 155–61. http://dx.doi.org/10.2113/jeeg14.4.155.

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Baniamerian, Jamaledin, Shuang Liu, Xiangyun Hu, Maurizio Fedi, Mahak Singh Chauhan und Mahmoud Ahmed Abbas. „Separation of magnetic anomalies into induced and remanent magnetization contributions“. Geophysical Prospecting 68, Nr. 7 (14.07.2020): 2320–42. http://dx.doi.org/10.1111/1365-2478.12993.

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Nyberg, Johan, Antoon Kuijpers, Björn A. Malmgren und Helmar Kunzendorf. „Late Holocene Changes in Precipitation and Hydrography Recorded in Marine Sediments from the Northeastern Caribbean Sea“. Quaternary Research 56, Nr. 1 (Juli 2001): 87–102. http://dx.doi.org/10.1006/qres.2001.2249.

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AbstractWe present a record of climate variability spanning the last 2000 years obtained from sediment cores retrieved south and west of Puerto Rico in the northeastern Caribbean Sea. The records include lithological and mineral magnetic parameters as well as planktonic foraminifer data. For chronostratigraphic control, AMS 14C and 210Pb/137Cs measurements were made. Harmonic analysis of the values of the mineral magnetic parameters “saturation isothermal remanent magnetization” (SIRM), “anhysteric remanent magnetization divided by magnetic susceptibility” (ARM/χ), and “saturation isothermal remanent magnetization divided by magnetic susceptibility” (SIRM/χ) indicate the existence of a ∼200-year-long climate cycle in the northeastern Caribbean during the last 2000 years. The detected cycle may reflect changes in precipitation patterns over the low-latitude North Atlantic Ocean and surrounding continental areas. Higher organic carbon contents appear in the sediments both off southern and western Puerto Rico before and at the onset of the Little Ice Age around A.D. 1300 to 1500. This is indicative of increased run off and/or enhanced surface productivity possibly associated with more intense wind-induced upwelling. Major changes in the geochemical and mineral magnetic records around A.D. 850–1000 concur with changes in other records from the Caribbean and North African regions indicating a shift toward a more humid climate over the low-latitude North Atlantic.

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Kiseleva, Tatiana Yu, Sergey I. Zholudev, Alla A. Novakova, Tatiana S. Gendler, Igor A. Il’inych, A. I. Smarzhevskaya, Yuriy Anufriev und Tatiana F. Grigorieva. „Magnetodeformational Anisotropy of FeGa/PU Hybrid Nanocomposite via Particle Concentration and Spatial Orientation“. Solid State Phenomena 233-234 (Juli 2015): 607–10. http://dx.doi.org/10.4028/www.scientific.net/ssp.233-234.607.

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The present work has been undertaken to research effects of structure, morphology, volume fraction, spatial arrangement of magnetostrictive intermetallic FeGa alloy particles dispersed in modified polyurethane matrix. Correlation of composite magnetic behavior with structure and mechanical properties has been obtained by measurements of magnetostriction, remanent magnetization anisotropy, SEM, and dynamical mechanical analysis. Anisotropic chain structures of magnetic particles within the polymer with different interparticle interactions were observed. The increase of the magnetostrictive response with tailor-made magnetic anisotropy induced by magnetic particles volume fraction has been demonstrated

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Wu, Biao, Lianwei Ren, Charles J. O'Connor, Jinke Tang, Jin-Seung Jung, Jacques Ferré und Jean-Pierre Jamet. „Photo-induced magnetic behavior in the amorphous spin-glass material Co3(SbTe3)2“. Journal of Materials Research 9, Nr. 4 (April 1994): 909–14. http://dx.doi.org/10.1557/jmr.1994.0909.

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A new ternary material Co3(SbTe3)2 was prepared by using a rapid precipitation metathesis reaction between the Zintl material K3SbTe3 and CoCl2 in aqueous solution. The dc specific resistivity of this material is in the region for metallic conductors (p = 2.75 × 10-3 Ω-cm). The dc magnetic susceptibility of Co3(SbTe3)2 is reported over a 2.2 K-300 K temperature region, and the material is characterized as a spin glass with a freezing temperature of about 5 K. Magnetization data are also reported as both thermal remanent magnetization and isothermal remanent magnetization as a function of magnetizing field and temperature. When cooled well below the glass freezing temperature, the frozen spin glass has been observed to exhibit photomagnetic effects consistent with a disruption of the spin-glass state caused by uv-radiation.

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Beason, Robert C., und William J. Brennan. „Natural and Induced Magnetization in the Bobolink, Dolichonyx Oryzivorus (Aves: Icteridae)“. Journal of Experimental Biology 125, Nr. 1 (01.09.1986): 49–56. http://dx.doi.org/10.1242/jeb.125.1.49.

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The magnetic characteristics of the heads from 28 bobolinks [Icteridae: Dolichonyx oryzivorus (L.)] were analysed using remanence magnetometers. The natural remanent magnetization of 12 freshly preserved heads averaged 3.20xl0−7 electromagnetic units (e.m.u.) (l e.m.u. = 103Am−1) and was oriented horizontally from side to side. An electromagnet was used to induce magnetization with external field strengths of up to O.7 Tesla (T). The average saturation isothermal remanent magnetization (sIRM) for 23 bobolink heads was 2.49×10−5e.m.u. Because the IRM was attained partially below 0.1 T and totally below 0.3 T, we believe that the magnetic material in the bobolink is at least partially single domain magnetite. The relationship between the IRM acquisition and alternating field (a.f.) demagnetization curves indicates that the single or pseudo-single domain grains of magnetite interact. Similar results were obtained on one savannah sparrow (Emberizidae: Passerculus sandwichensis) head and one indigo bunting (Emberizidae: Passerine cyanea) head. When some bobolink heads were subdivided, most or all of the magnetization was concentrated in the area from the nasal cavity to the orbit. Light microscopy and histochemical tests confirm the localization of inorganic iron in this region.

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Sternberg, Robert S. „Archaeomagnetism and magnetic anomalies in the American Southwest“. GEOPHYSICS 52, Nr. 3 (März 1987): 368–71. http://dx.doi.org/10.1190/1.1442311.

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Magnetic surveying is probably the most widely used geophysical technique at archaeological sites (Weymouth and Huggins, 1985). It is useful for locating features in which the magnetic susceptibility contrasts with the magnetic susceptibility of the surroundings because of induced and/or remanent magnetization. A contrast in magnetic induction can arise, for example, when the disturbed soil fill inside a formerly occupied room has a different magnetic susceptibility from the subsoil outside the room (Tite and Mullins, 1971). A contrast in magnetic remanence most commonly occurs when a baked clay artifact or feature such as a hearth has acquired a thermoremanent magnetization after being heated to several hundred degrees Celsius.

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Cohen, Yves, und Jose Achache. „Contribution of induced and remanent magnetization to long-wavelength oceanic magnetic anomalies“. Journal of Geophysical Research: Solid Earth 99, B2 (10.02.1994): 2943–54. http://dx.doi.org/10.1029/92jb01850.

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Mariano, John, und William J. Hinze. „Gravity and magnetic models of the Midcontinent Rift in eastern Lake Superior“. Canadian Journal of Earth Sciences 31, Nr. 4 (01.04.1994): 661–74. http://dx.doi.org/10.1139/e94-059.

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Gravity and magnetic models of the Midcontinent Rift (MCR) in eastern Lake Superior supplement recent structural and stratigraphic interpretations based on the seismic reflection method. An algorithm developed to accommodate spatially varying direction and magnitude of magnetization within a magnetic source is used in both forward and inverse modeling procedures. Structural attitudes of rift-filling basalts derived from seismic reflection sections are used to rotate the Keweenawan remanent magnetization vectors in the direction of deformation. An iterative linear inversion routine calculates magnitudes of induced and remanent magnetizations, as well as normal and reversed polarity basalt flow distributions. The results indicate that the Koenigsberger ratios of these basalts generally range from 1 to 3, which is in agreement with values obtained from rock property measurements. The models also suggest that the greater volume of the Keweenawan basalt section in eastern Lake Superior is reversely polarized and that remanent magnetizations persist to depths of up to 20 km. Our results, supplemented by isotopic and paleomagnetic data, suggest that the vast majority of the basalts predate 1097 ± 1 Ma. A prominent positive magnetic anomaly and a corresponding gravity low strike west across the trend of the rift from the vicinity of Michipicoten Island. These anomalies may reflect a relatively strongly magnetized, felsic igneous body of late-middle to upper Keweenawan in age. Forward gravity models suggest clastic sedimentary rocks up to several kilometers thick overlay the volcanic rocks in localized depressions. Deep crustal seismic data used to constrain gravity models provide evidence of anomalously dense lower crust beneath the MCR.

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Gallet, Yves, und Vincent Courtillot. „Modeling magnetostratigraphy in a borehole“. GEOPHYSICS 54, Nr. 8 (August 1989): 973–83. http://dx.doi.org/10.1190/1.1442740.

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The magnetic field along a hole bored through a sequence of dipping layers with varying magnetization and planar interfaces is calculated. The emphasis is on recovering remanent magnetization polarity transitions for magnetostratigraphic applications (dating, correlations), although intensity of remanent magnetization can in itself be a useful rock property. Results are presented for various cases of geologic interest in the form of axial vertical profiles and section maps of the holes at varying distances from polarity reversal interfaces. The vertical profiles demonstrate a resolving power of about six times the hole radius; meaningful magnetostratigraphies can be expected for rocks with a magnetization larger than [Formula: see text], for instruments with a sensitivity of 0.1 nT. In a number of natural occurrences, it may not be necessary to resort to progressive demagnetization to recover the polarity sequence. Depending on which magnetic field and magnetization component one looks at, the section maps display characteristic patterns, in which, for instance, the direction of magnetization and the dip of the layers interfere. These maps are discussed in some detail. They can be used as guidelines to build a multisensor vector magnetometer (downhole magnetostratigraphic tool), whose output should be coupled with measurement of magnetic susceptibility for reduction of induced magnetization and with output from a surface instrument in a differential operation mode to reduce transient magnetic variations.

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Chen, Zhong Yan, Yuan Zhou, Fu Chen und Ze Kun Feng. „Influence of Microwave Calcination on Microstructure and Magnetic Properties of Sr-Hexagonal Ferrite“. Advanced Materials Research 668 (März 2013): 741–44. http://dx.doi.org/10.4028/www.scientific.net/amr.668.741.

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The improvement of the microstructure of Sr-hexagonal ferrite and their magnetic properties by microwave calcined method was studied, the aim of the study was to obtain a fine grained microstructure in calcined stage. There was tendency to induce a large anisotropic during grain growth, microwave calcination method can succeed in obtaining homogeneous grain growth ,and help to reduce the calcination temperature and shorten the calcination time. The ferrites with saturation magnetization, remanent magnetization and intrinsic coercivity of 70.322emu/g, 36.182emu/g, 3343.1Oe, respectively, obtained in samples calcined at 1140°C for 30 min.

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Shi, Lei, Liang Hui Guo und 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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de Souza, Jeferson, Saulo Pomponet Oliveira und Francisco José Fonseca Ferreira. „Using parity decomposition for interpreting magnetic anomalies from dikes having arbitrary dip angles, induced and remanent magnetization“. GEOPHYSICS 85, Nr. 3 (28.04.2020): J51—J58. http://dx.doi.org/10.1190/geo2019-0225.1.

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We have developed a technique to reconstruct the magnetic anomaly due to a dike in a way that the effect of magnetization direction is removed, resulting in a new totally symmetric anomaly. The reconstruction algorithm is easy to implement and could avoid the need of reduction to the pole at a low computational cost. The method is based on the decomposition of the function representing magnetic anomalies due to dikes in its even and odd parts. After applying a Hilbert transform to the odd components, we reconstruct the signal by a weighted average of the even part and the Hilbert-transformed odd part of the signal. The method requires knowing the dike’s center position, which is accomplished by locating the center of symmetry of the analytic signal amplitude as well as the effective dip angle obtained by evaluating the anomaly’s tilt angle. Our approach is tested for synthetic and field data. As an illustration of the method’s potential applications, we use it to estimate the width and depth of magnetic dikes.

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Furuya, Kazuo, Masaki Takeguchi und Kazutaka Mitsuishi. „Iron Nanostructures Fabricated by Electron Beam Induced Deposition and its Magnetic Properties“. Solid State Phenomena 124-126 (Juni 2007): 139–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.139.

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Electron beam induced deposition (EBID) was carried out with gas introduction systems attached to field emission scanning electron microscope (FE-SEM). Using iron carbonyl and ferrocene, three dimensional (3-D) antenna structures were fabricated in the range of 30-50 nm in diameter and 500-1000 nm in size. Post-deposition annealing of iron nanostructures resulted in the formation of crystalline alpha-iron and iron carbide phases. The iron concentration was controlled by the partial pressure of iron carbonyl and ferrocene. Electron holography observation with field emission transmission electron microscopy (FE-TEM) revealed that the remanent magnetic flux density Br of the nanostructures also depends on the iron concentration.

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Sangiao, Soraya, César Magén, Darius Mofakhami, Grégoire de Loubens und José María De Teresa. „Magnetic properties of optimized cobalt nanospheres grown by focused electron beam induced deposition (FEBID) on cantilever tips“. Beilstein Journal of Nanotechnology 8 (09.10.2017): 2106–15. http://dx.doi.org/10.3762/bjnano.8.210.

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In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID). The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM) experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm. Electron holography measurements show the formation of a magnetic vortex state in remanence, which nicely agrees with magnetic hysteresis loops performed by local magnetometry showing negligible remanent magnetization. As investigated by local magnetometry, optimal behavior for high-resolution MRFM has been found for cobalt nanospheres with a diameter of ≈200 nm, which present atomic cobalt content of ≈83 atom % and saturation magnetization of 106 A/m, around 70% of the bulk value. These results represent the first comprehensive investigation of the magnetic properties of cobalt nanospheres grown by FEBID for application in MRFM.

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Baykiev, Eldar, Jörg Ebbing, Marco Brönner und Karl Fabian. „Forward modeling magnetic fields of induced and remanent magnetization in the lithosphere using tesseroids“. Computers & Geosciences 96 (November 2016): 124–35. http://dx.doi.org/10.1016/j.cageo.2016.08.004.

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Dobrovolskiy, Oleksandr V., Maksym Kompaniiets, Roland Sachser, Fabrizio Porrati, Christian Gspan, Harald Plank und Michael Huth. „Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures“. Beilstein Journal of Nanotechnology 6 (29.04.2015): 1082–90. http://dx.doi.org/10.3762/bjnano.6.109.

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Controlling magnetic properties on the nanometer-scale is essential for basic research in micro-magnetism and spin-dependent transport, as well as for various applications such as magnetic recording, imaging and sensing. This has been accomplished to a very high degree by means of layered heterostructures in the vertical dimension. Here we present a complementary approach that allows for a controlled tuning of the magnetic properties of Co/Pt heterostructures on the lateral mesoscale. By means of in situ post-processing of Pt- and Co-based nano-stripes prepared by focused electron beam induced deposition (FEBID) we are able to locally tune their coercive field and remanent magnetization. Whereas single Co-FEBID nano-stripes show no hysteresis, we find hard-magnetic behavior for post-processed Co/Pt nano-stripes with coercive fields up to 850 Oe. We attribute the observed effects to the locally controlled formation of the CoPt L10 phase, whose presence has been revealed by transmission electron microscopy.

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CHEN, H. Z., M. C. KAO und S. L. YOUNG. „MAGNETIC AND STRUCTURAL TRANSITION PROPERTIES OF NIOBIUM-DOPED BiFeO3 THIN FILMS“. International Journal of Modern Physics B 27, Nr. 15 (04.06.2013): 1362003. http://dx.doi.org/10.1142/s0217979213620038.

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Niobium-substituted BiFeO 3( BiFe 1-x Nb x O 3 BFNO ) thin films were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates by spin coating with a sol–gel technology and rapid thermal annealing. The effects of Nb content (x = 0~0.08) on the microstructure, magnetic and multiferroic properties of thin films were investigated. The result of X-ray diffraction analysis shows that the BFNO thin films have rhombohedral (R3c) to tetragonal (P4mm) phase transition at x = 0.06. The Nb doping in the B-site of BiFeO 3 could induce the appearance of the spontaneous magnetization and polarization by the phase transition of rhombohedral-to-tetragonal. The BFNO thin films with x = 0.06 exhibits the maximum remanent magnetization (2Mr) of 5.2 emu/g.

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Санина, В. А., Б. Х. Ханнанов, Е. И. Головенчиц und М. П. Щеглов. „Электрическая поляризация в YCrO-=SUB=-3-=/SUB=-, индуцированная локальными полярными областями магнитной и структурной природы“. Физика твердого тела 61, Nr. 1 (2019): 95. http://dx.doi.org/10.21883/ftt.2019.01.46899.213.

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AbstractThe electric polarization induced by local polar domains of two types (phase separation domains of magnetic nature and structure-distorted domains) has been observed in a YCrO_3 single crystal. These domains form a superparaelectric state. Below some temperatures, in the frozen superparaelectric state, the pyrocurrent maxima and the hysteresis loops with remanent polarization are observed as along axis c so in directions [110]. The polarization exists to the temperatures depending on the orientation of electric field with respect to the crystal axes. The sources of formation of such local domains are analyzed and their properties are studied.

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Lesur, V., und D. Gubbins. „Using geomagnetic secular variation to separate remanent and induced sources of the crustal magnetic field“. Geophysical Journal International 142, Nr. 3 (01.09.2000): 889–97. http://dx.doi.org/10.1046/j.1365-246x.2000.00190.x.

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Straka, L., A. Soroka, O. Heczko, H. Hänninen und A. Sozinov. „Mechanically induced demagnetization and remanent magnetization rotation in Ni–Mn–Ga (–B) magnetic shape memory alloy“. Scripta Materialia 87 (September 2014): 25–28. http://dx.doi.org/10.1016/j.scriptamat.2014.05.017.

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McEnroe, Suzanne A., Laurie L. Brown und Peter Robinson. „Remanent and induced magnetic anomalies over a layered intrusion: Effects from crystal fractionation and magma recharge“. Tectonophysics 478, Nr. 1-2 (November 2009): 119–34. http://dx.doi.org/10.1016/j.tecto.2008.11.021.

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Robinson, Peter, S. A. McEnroe, R. J. Harrison, K. Fabian, F. Heidelbach und M. Jackson. „Lamellar magnetism and exchange bias in billion-year-old metamorphic titanohematite with nanoscale ilmenite exsolution lamellae – III. Atomic-magnetic basis for experimental results“. Geophysical Journal International 226, Nr. 2 (29.04.2021): 1348–67. http://dx.doi.org/10.1093/gji/ggab176.

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SUMMARY Lamellar magnetism is a source of remanent magnetization in natural rocks different from common bulk magnetic moments in ferrimagnetic minerals. It has been found to be a source for a wide class of magnetic anomalies with extremely high Koenigsberger ratio. Its physical origin are uncompensated interface moments in contact layers of nanoscale ilmenite lamellae inside an hematite host, which also generate unusual low-temperature (low-T) magnetic properties, such as shifted low-T hysteresis loops due to exchange bias. The atomic-magnetic basis for the exchange bias discovered in the hematite-ilmenite system is explored in a series of papers. In this third article of the series, simple models are developed for lamellae interactions of different structures when samples are either cooled in zero-field, or field-cooled in 5 T to temperatures below the ordering temperature of ilmenite. These models are built on the low-temperature measurements described earlier in Paper II. The important observations include: (i) the effects of lamellar shapes on magnetic coupling, (ii) the high-T acquisition of lamellar magnetism and low-T acquisition of magnetization of ilmenite lamellae, (iii) the intensity of lamellar magnetism and the consequent ilmenite magnetism in populations of randomly oriented crystals, (iv) lattice-preferred orientation of the titanohematite host crystal populations and (v) the effects of magnetic domain walls in the host on hysteresis properties. Based on exemplary growth models of lamellae with different geometries and surface couplings we here provide simple models to assess and explain the different observations listed above. Already the simplified models show that the shapes of the edges of ilmenite lamellae against their hematite hosts can control the degree of low-T coupling between ilmenite, and the lamellar magnetic moments. The models also explain certain features of the low-T exchange bias in the natural samples and emphasize the role of lattice-preferred orientation upon the intensity of remanent magnetization. The inverse link between ilmenite remanence and exchange-bias shift in bimodal low-T ilmenite lamellae is related to different densities of hematite domain walls induced by the clusters of ilmenite lamellae.

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Dannemiller, Neal, und Yaoguo Li. „A new method for determination of magnetization direction“. GEOPHYSICS 71, Nr. 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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Kurniawan, Candra, Agus Tri Widodo, Dong Hyun Kim und Dede Djuhana. „Micromagnetic Investigation of Magnetization Reversal in Sphere-Shaped Ferromagnetic Nanoparticle“. Key Engineering Materials 855 (Juli 2020): 237–42. http://dx.doi.org/10.4028/www.scientific.net/kem.855.237.

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In this paper, the magnetization reversal of sphere-shaped ferromagnetic nanoparticles has been investigated by means of micromagnetic simulation. Some ferromagnetic particles such as Cobalt, Iron, Nickel, and Permalloy were modeled with size variation from 50 nm to 100 nm. The discretization of the ferromagnetic model was used a cell size of 2.5×2.5×2.5 nm3 considering the exchange length (lex) of the materials. The quasi-static magnetic field was induced into the nanosphere to observe the magnetization response under time dependence. It is found that the coercivity values are decreased as the sphere size increased, which was conformed the experimental results. It is also observed that the domain structure of a single particle in remanent and ground-state condition are identical. Therefore, the specific understanding of magnetization process and domain structures in ferromagnetic nanoparticles could be an important step in the development of nanopatterned magnetic memory storage.

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NARSINGA RAO, G., P. MOLINIE, M. GANNE und D. SURESH BABU. „MAGNETIC RELAXATION, LOWER CRITICAL FIELD AND IRREVERSIBILITY LINE OF W DOPED (Bi, Pb)-2223 SUPERCONDUCTOR“. Modern Physics Letters B 09, Nr. 21 (10.09.1995): 1387–96. http://dx.doi.org/10.1142/s0217984995001388.

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We report magnetic relaxation, lower critical field and irreversibility line studies of a single phase W doped (Bi,Pb)-2223 superconductor. The temperature dependence of remanent magnetization exhibited a rapid drop at T ≤ 20 K and was due to the drastic decrease of critical current density (J c ). The activation energy U0 determined from magnetic relaxation measurements showed that there exists two types of pinning centres in the vortex lattice. The temperature dependence of lower critical field (H c1 ) exhibited a kink around 25 K. Possible reasons for exhibited anomaly in H c1 were discussed. The irreversibility line exhibited an exponential decrease with increasing temperature and is due to the existence of break down field of proximity effect, induced superconductivity in layered HTSC. Fermi velocity in superconductivity regions (V FN ) is found to be a factor of ten larger than that in normal regions (V FN ).

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Yang, C. J. „Texture Induced Magnetic Anisotropy in Fe–Nd–B Magnets Prepared via Rapid Solidification and Hot Extrusion Techniques“. Textures and Microstructures 11, Nr. 2-4 (01.01.1989): 143–58. http://dx.doi.org/10.1155/tsm.11.143.

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High performance Fe–Nd–B magnets were prepared by consolidation of rapidly solidified melt spun powder using a hot extrusion technique. The extrusion was carried out with various die openings to control the distribution of stresses and strains influencing the possible development of texture. A strong anisotropy in magnetic properties has been found in the extruded magnets. The highest remanence of 10.6 kG and the maximum energy product of 16.6 MGOe were achieved along the through-thickness direction of the magnet extruded into a rectangular cross section. A (001) [1¯20] texture was found to develop in the plane normal to the through-thickness direction. It is suggested that the enhanced remanent magnetization arises principally from the formation of favorable texture.

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Hart, R. D., T. G. St Pierre, R. J. Gilkes, A. J. McKinley, S. Siradz und Balwant Singh. „Iron in soil kaolins from Indonesia and Western Australia“. Clay Minerals 37, Nr. 4 (Dezember 2002): 671–85. http://dx.doi.org/10.1180/0009855023740069.

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AbstractSoil kaolins from Indonesia and Western Australia and a range of reference kaolins were studied using Mössbauer spectroscopy, electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry. Mössbauer spectra indicate that the Fe within the kaolins is in the highspin Fe3+oxidation state and that a large fraction of the Fe is present as dispersed atoms residing within the octahedral sites of the kaolinite crystal structure. The EPR spectra are typical for soil kaolins except for the absence of radiation-induced defects for the Indonesian kaolins. The Fe(I)spectra are dominant with a strong symmetric peak atg= 4.3, the presence of Fe(II) spectra is shown by a shoulder on this peak atg= 4.9 and a small phase up peak atg= 9.2.Low-temperature (5 K) magnetization (M) measurements over large field (H) sweeps (±70 kOe) yieldedM(H) curves which are fitted well with Brillouin functions indicating the paramagnetic nature of the kaolins at temperatures down to 5 K. A very small remanent magnetization was detectable in the kaolins. Remanent magnetization to saturation magnetization ratios ranged from 10–4to 10–3for the Indonesian kaolins and were all ∼10–3for the Western Australian kaolins, indicating that at high fields the vast majority of the magnetization of the kaolins is due to paramagnetic ions.Zero-field-cooled and field-cooled magnetization measurements in small fields (500 Oe) indicate that the Indonesian kaolins are generally free from magnetically-blocked material down to a temperature of 5 K. The magnetic susceptibility of the Indonesian kaolins shows Curie Law behaviour indicating paramagnetic behaviour over all temperatures down to 5 K. Measurements on the Western Australian kaolins indicated the presence of some magnetic material that is magnetically blocked at temperatures below ∼200 250 K. As a consequence, the magnetic susceptibility showed large deviations from Curie Law behaviour.

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Alekhina, Iuliia, Valeria Kolesnikova, Vladimir Rodionov, Nikolai Andreev, Larissa Panina, Valeria Rodionova und Nikolai Perov. „An Indirect Method of Micromagnetic Structure Estimation in Microwires“. Nanomaterials 11, Nr. 2 (21.01.2021): 274. http://dx.doi.org/10.3390/nano11020274.

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The tunable magnetic properties of amorphous ferromagnetic glass-coated microwires make them suitable for a wide range of applications. Accurate knowledge of the micromagnetic structure is highly desirable since it affects almost all magnetic properties. To select an appropriate wire-sample for a specific application, a deeper understanding of the magnetization reversal process is required, because it determines the measurable response (such as induced voltage waveform and its spectrum). However, the experimental observation of micromagnetic structure of micro-scale amorphous objects has strict size limitations. In this work we proposed a novel experimental technique for evaluating the microstructural characteristics of glass-coated microwires. The cross-sectional permeability distribution in the sample was obtained from impedance measurements at different frequencies. This distribution enables estimation of the prevailing anisotropy in the local region of the wire cross-section. The results obtained were compared with the findings of magnetostatic measurements and remanent state analysis. The advantages and limitations of the methods were discussed.

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Isezaki, Nobuhiro. „A new shipboard three‐component magnetometer“. GEOPHYSICS 51, Nr. 10 (Oktober 1986): 1992–98. http://dx.doi.org/10.1190/1.1442054.

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The three components of the geomagnetic field were measured at sea by STCM (Shipboard Three Component Magnetometer) with a relative accuracy of 50 ± 25 nT. The STCM was controlled by a microcomputer, and the three geomagnetic components were calculated by reducing the magnetic field due to the ship’s remanent and induced magnetic moments, the only assumption being that the magnetic field is linearly related to the magnetic moments. Although STCM has no particular magnetic compensation device, it can be set at any place on board of any kind of ship. In the KH82-5 cruise, the three component measurements were conducted along latitude 42 °N north of the Mendocino fracture zone where there are well‐defined magnetic anomaly lineations trending north and south. STCM measured the north component anomalies with very small amplitudes compared to the east and downward component anomalies, which shows that lineations trend north and south. The three measured component anomalies are almost identical to the anomalies calculated from the well‐established time scale; thus, STCM measures the three components correctly. The vector geomagnetic measurements are more useful for analysis of marine geomagnetic anomalies than are the total‐intensity measurements. The DELPWAKASHIO 84/1 cruises provide good examples for examination of the linearity of magnetic anomalies on a single track by using the Fourier transform of the horizontal and vertical component anomalies.

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Wohlgenannt, M., M. E. Flatté, N. J. Harmon, F. Wang, A. D. Kent und F. Macià. „Singlet-to-triplet interconversion using hyperfine as well as ferromagnetic fringe fields“. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, Nr. 2044 (28.06.2015): 20140326. http://dx.doi.org/10.1098/rsta.2014.0326.

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Until recently the important role that spin-physics (‘spintronics’) plays in organic light-emitting devices and photovoltaic cells was not sufficiently recognized. This attitude has begun to change. We review our recent work that shows that spatially rapidly varying local magnetic fields that may be present in the organic layer dramatically affect electronic transport properties and electroluminescence efficiency. Competition between spin-dynamics due to these spatially varying fields and an applied, spatially homogeneous magnetic field leads to large magnetoresistance, even at room temperature where the thermodynamic influences of the resulting nuclear and electronic Zeeman splittings are negligible. Spatially rapidly varying local magnetic fields are naturally present in many organic materials in the form of nuclear hyperfine fields, but we will also review a second method of controlling the electrical conductivity/electroluminescence, using the spatially varying magnetic fringe fields of a magnetically unsaturated ferromagnet. Fringe-field magnetoresistance has a magnitude of several per cent and is hysteretic and anisotropic. This new method of control is sensitive to even remanent magnetic states, leading to different conductivity/electroluminescence values in the absence of an applied field. We briefly review a model based on fringe-field-induced polaron-pair spin-dynamics that successfully describes several key features of the experimental fringe-field magnetoresistance and magnetoelectroluminescence.

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Garnier, L. C., M. Eddrief, S. Fin, D. Bisero, F. Fortuna, V. H. Etgens und M. Marangolo. „Perpendicular Magnetic Anisotropy in Fe–N Thin Films: Threshold Field for Irreversible Magnetic Stripe Domain Rotation“. SPIN 06, Nr. 04 (Dezember 2016): 1640014. http://dx.doi.org/10.1142/s2010324716400142.

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The magnetic properties of an iron nitride thin film obtained by ion implantation have been investigated. N[Formula: see text] ions were implanted in a pristine iron layer epitaxially grown on ZnSe/GaAs(001). X-ray diffraction measurements revealed the formation of body-centered tetragonal N-martensite whose [Formula: see text]-axis is perpendicular to the thin film plane and [Formula: see text]-parameter is close to that of [Formula: see text]-Fe8N. Magnetic measurements disclosed a weak perpendicular magnetic anisotropy (PMA) whose energy density [Formula: see text] was assessed to about 105[Formula: see text]J/m3. A sharp decline of the in-plane magnetocrystalline anisotropy (MCA) was also observed, in comparison with the body-centered cubic iron. The origin of the PMA is attributed to the MCA of N-martensite and/or stress-induced anisotropy. As a result of the PMA, weak magnetic stripe domains with a period of about 130[Formula: see text]nm aligned along the last saturating magnetic field direction were observed at remanence by magnetic force microscopy. The application of an increasing in-plane magnetic field transverse to the stripes [Formula: see text] highlighted a threshold value ([Formula: see text][Formula: see text]T) above which these magnetic domains irreversibly rotated. Interestingly, below this threshold, the stripes do not rotate, leading to a zero remanent magnetization along the direction of the applied field. The interest of this system for magnetization dynamics is discussed.

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Petrila, Iulian, und Florin Tudorache. „The Influence of Li+ and K+ Added Cations and Annealing Temperature on the Magnetic and Dielectric Properties of Mg-Zn Ferrite“. Materials 14, Nr. 17 (29.08.2021): 4916. http://dx.doi.org/10.3390/ma14174916.

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This paper presents the results of an investigation on the magnetic and dielectric properties of Mg0.5Zn0.5Fe2O4 spinel ferrite with a 1% weight percentage of Li+ and K+ added cations. The addition of metal ions plays an important role in increasing the porosity and favors the formation of ferrite at low temperatures. The goal of this new research is to demonstrate that by selecting the type of metallic cations for addition or choosing an optimal sintering temperature, it may be possible to improve the magnetic and electrical properties of Mg-Zn ferrite. The samples were prepared using sol-gel self-combustion techniques and annealed at 1000 °C, 1100 °C, and 1200 °C. Scanning electron microscopy revealed the shape and grain size of the samples, and the phase composition was analyzed using the X-ray diffraction technique. The magnetic information, such as remanent magnetization MR, saturation magnetization MS, and coercivity HC, were extracted from the hysteresis loops of the samples. The electrical investigation was focused on the low- and high-frequency dependence of dielectric constant and dielectric losses. The results are discussed in terms of microstructural changes induced by the additions of Li+ and K+ metallic cations. Conclusions are drawn concerning the optimization of magnetic and electrical properties for the development of Mg-Zn ferrite with possible applications in the field of magnetic materials or electronics.

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Maksym, Geoffrey N., Ben Fabry, James P. Butler, Daniel Navajas, Daniel J. Tschumperlin, Johanne D. Laporte und Jeffrey J. Fredberg. „Mechanical properties of cultured human airway smooth muscle cells from 0.05 to 0.4 Hz“. Journal of Applied Physiology 89, Nr. 4 (01.10.2000): 1619–32. http://dx.doi.org/10.1152/jappl.2000.89.4.1619.

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We investigated the rheological properties of living human airway smooth muscle cells in culture and monitored the changes in rheological properties induced by exogenous stimuli. We oscillated small magnetic microbeads bound specifically to integrin receptors and computed the storage modulus (G′) and loss modulus (G") from the applied torque and the resulting rotational motion of the beads as determined from their remanent magnetic field. Under baseline conditions, G′ increased weakly with frequency, whereas G" was independent of the frequency. The cell was predominantly elastic, with the ratio of G" to G′ (defined as η) being ∼0.35 at all frequencies. G′ and G" increased together after contractile activation and decreased together after deactivation, whereas η remained unaltered in each case. Thus elastic and dissipative stresses were coupled during changes in contractile activation. G′ and G" decreased with disruption of the actin fibers by cytochalasin D, but η increased. These results imply that the mechanisms for frictional energy loss and elastic energy storage in the living cell are coupled and reside within the cytoskeleton.

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Wakiya, Naoki, Kan Shimizu, Satoshi Mizukami, Kazuo Shinozaki und Nobuyasu Mizutani. „Modification of drain current on metal–oxide–semiconductor field-effect transistor by magnetic field induced by remanent magnetization“. Applied Physics Letters 85, Nr. 17 (25.10.2004): 3772–74. http://dx.doi.org/10.1063/1.1812382.

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Jorgensen, Michael, und Michael Zhdanov. „Recovering Magnetization of Rock Formations by Jointly Inverting Airborne Gravity Gradiometry and Total Magnetic Intensity Data“. Minerals 11, Nr. 4 (31.03.2021): 366. http://dx.doi.org/10.3390/min11040366.

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Conventional 3D magnetic inversion methods are based on the assumption that there is no remanent magnetization, and the inversion is run for magnetic susceptibility only. This approach is well-suited to targeting mineralization; however, it ignores the situation where the direction of magnetization of the rock formations is different from the direction of the induced magnetic field. We present a novel method of recovering a spatial distribution of magnetization vector within the rock formation based on joint inversion of airborne gravity gradiometry (AGG) and total magnetic intensity (TMI) data for a shared earth model. Increasing the number of inversion parameters (the scalar components of magnetization vector) results in a higher degree of non-uniqueness of the inverse problem. This increase of non-uniqueness rate can be remedied by joint inversion based on (1) Gramian constraints or (2) joint focusing stabilizers. The Gramian constraints enforce shared earth structure through a correlation of the model gradients. The joint focusing stabilizers also enforce the structural similarity and are implemented using minimum support or minimum gradient support approaches. Both novel approaches are applied to the interpretation of the airborne data collected over the Thunderbird V-Ti-Fe deposit in Ontario, Canada. By combining the complementary AGG and TMI data, we generate jointly inverted shared earth models that provide a congruent image of the rock formations hosting the mineral deposit.

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Li, Yaoguo, und Douglas W. Oldenburg. „3-D inversion of magnetic data“. GEOPHYSICS 61, Nr. 2 (März 1996): 394–408. http://dx.doi.org/10.1190/1.1443968.

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We present a method for inverting surface magnetic data to recover 3-D susceptibility models. To allow the maximum flexibility for the model to represent geologically realistic structures, we discretize the 3-D model region into a set of rectangular cells, each having a constant susceptibility. The number of cells is generally far greater than the number of the data available, and thus we solve an underdetermined problem. Solutions are obtained by minimizing a global objective function composed of the model objective function and data misfit. The algorithm can incorporate a priori information into the model objective function by using one or more appropriate weighting functions. The model for inversion can be either susceptibility or its logarithm. If susceptibility is chosen, a positivity constraint is imposed to reduce the nonuniqueness and to maintain physical realizability. Our algorithm assumes that there is no remanent magnetization and that the magnetic data are produced by induced magnetization only. All minimizations are carried out with a subspace approach where only a small number of search vectors is used at each iteration. This obviates the need to solve a large system of equations directly, and hence earth models with many cells can be solved on a deskside workstation. The algorithm is tested on synthetic examples and on a field data set.

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Felner, I., und E. Galstyan. „Decoupling of the Magnetic State in RuSr2Eu1.5Ce0.5Cu2O10-δ“. International Journal of Modern Physics B 17, Nr. 18n20 (10.08.2003): 3617–21. http://dx.doi.org/10.1142/s0217979203021502.

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We have studied the effect of Zn substitution for Cu, on the superconducting (SC) and magnetic properties of RuSr 2 Eu 2-x Ce x( Cu 1-x Zn x)2 O 10 (Ru-1222) for x = 0, 0.01 and 0.025. Similar to all other Zn doped HTSC materials, Zn reduces TC, from TC = 38 to 26 K for x = 0 and 0.01 respectively. The system with x = 0.025 is not SC down to 4.2 K. On the other hand, the magnetic state of the Ru sublattice is not significantly affected by the presence or absence the SC State. Thus, the two states are practically decoupled. The wide ferromagnetic hysteresis loops which open at 5 K close themselves at elevated temperatures and the remanent magnetizations (Mrem) and the coercive fields (HC) become zero around Tirr = 80 K . Surprisingly, at Tirr < T < TM a reappearance of the Mrem and HC (with a peak at 120 K) is observed for all three samples studied. We argue that the Ru-1222 system becomes (i) Anti-ferromagnetically (AFM) ordered at TM. (ii) At Tirr < TM, weak-ferromagnetism (W–FM) is induced by the canting of the Ru moments. (iii) At TC (TM/TC ~ 4), the system becomes SC and both SC and W–FM states coexist.

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Louro, Vinicius Hector Abud, Marta Silvia Maria Mantovani und Vanessa Biondo Ribeiro. „Magnetic field analysis of Morro do Leme nickel deposit“. GEOPHYSICS 79, Nr. 6 (01.11.2014): K1—K9. http://dx.doi.org/10.1190/geo2014-0131.1.

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The Morro do Leme laterite nickel deposit lies inside the western border of the Parecis Basin (Brazil). This deposit is characterized by high concentrations of lateritic Ni (about 1.8%) and anomalous contents of Pd, Au, Cu, Na, Co, Zn, and Pt in a peridotite and dunite layered intrusion. Besides the existence of geochemical and drilling data, the 3D distribution in the subsurface of this layered intrusion is still unknown. An airborne magnetic survey revealed three east–west elongated magnetic anomalies, characterized by a significant remanent magnetization. The sources of these anomalies were delimitated laterally and had their depths estimated between 90 and 150 m, using techniques that use derivatives. Further, the total magnetization direction was obtained from a distortion analysis of the magnetic anomalies. All these data were united in an initial model for the 3D inversion of the magnetic data. The total and induced magnetization directions were attributed to the inverted model of 0.12 (SI) susceptibility, allowing indirect estimation of the remanence. The model, defined by the depth, the inversion, and the remanence estimates, linked the intrusion to analogue events in the Rondonian-San Ignácio Province. The results indicated that to explore for laterite Ni, the best locations are the southern part of the main anomaly and in the cover above the two smaller anomalies, whereas to explore for Pd, Au, Cu, Na, Co, Zn, and/or Pt, the indicated region is the central portion of the main anomaly.

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Wigh, Mark David, Thomas Mejer Hansen und Arne Døssing. „Inference of unexploded ordnance (UXO) by probabilistic inversion of magnetic data“. Geophysical Journal International 220, Nr. 1 (19.10.2019): 37–58. http://dx.doi.org/10.1093/gji/ggz421.

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SUMMARY Magnetic modelling of unexploded ordnance (UXO) is a well-documented method used to interpret magnetic anomalies occurring in UXO excavation surveys. By treating UXO as a ferrous spheroidal object, the induced dipole moment can be estimated by approximation of UXO characteristics such as shape, size and orientation. Inversion of magnetic data with respect to UXO requires one to solve the equation for the induced dipole moment, while also determining the location and orientation of the object. This is a highly nonlinear, non-unique problem, where many solutions often are present, which make it difficult for standard inversion methods, such as linearized approaches and maximum likelihood estimators, in assessing uncertainties and correlations in estimated model parameters that often result in an incomplete solution. In this study, we treat the problem concerning magnetic UXO inversion by a probabilistic approach using Markov chain Monte Carlo (McMC) sampling. To deal with the potential multimodality, a combination of two well-known McMC sampling methods is employed in a single-chain approach: the extended Metropolis algorithm is used for efficient local sampling, and the Gibbs sampler is used to help exploring the possible multimodal density of the posterior. By adding a Gibbs step we significantly increase the efficiency of the extended Metropolis, making it viable to use as a single-chain sampler for this problem. We refer to the algorithm as the Gibbs-within-Metropolis algorithm. We test and compare the proposed algorithm to a multichain McMC parallel tempering setup using the extended Metropolis algorithm. We then present synthetic cases and a real data case, where the algorithm is used. We demonstrate how the probabilistic approach allows full inference of the parameters describing a UXO while also including the possible presence of remanent magnetization.

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Санина, В. А., Б. Х. Ханнанов, Е. И. Головенчиц und М. П. Щеглов. „Электрическая поляризация в ErCrO-=SUB=-3-=/SUB=-, индуцированная локальными полярными областями“. Физика твердого тела 61, Nr. 3 (2019): 501. http://dx.doi.org/10.21883/ftt.2019.03.47242.286.

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AbstractElectric polarization in ErCrO_3 single crystals has been investigated in the temperature range of 5‒370 K. Ferroelectric ordering has not been found in any of the directions. However, electric polarization induced by restricted polar domains of structural origin has been observed. These domains are formed in the crystal matrix near impurity Bi^3+ ions partially substituting Er^3+ ions during the growth of single crystals by the method of spontaneous crystallization using solvent Bi_2O_3. The restricted polar domains form the superparaelectric state. Hysteresis loops with remanent polarization, both along the c axis and in the [110] directions, have been observed below some temperatures T _fr (in the frozen superparaelectric state). The polarization exists up to certain temperatures, which depend on the applied electric field orientation with respect to the crystal axes and exceed significantly temperature T _N of magnetic ordering. These temperatures correspond to the condition kT _fr ≈ E _A for activation barriers at the boundaries of the restricted polar domains.

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Peng, Qi, Junjie Huang, Mingxiang Chen und Qingping Sun. „Phase-field simulation of magnetic hysteresis and mechanically induced remanent magnetization rotation in Ni-Mn-Ga ferromagnetic shape memory alloy“. Scripta Materialia 127 (Januar 2017): 49–53. http://dx.doi.org/10.1016/j.scriptamat.2016.08.033.

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Shimizu, Hisayoshi, Takao Koyama, Shigeru Koyama und Hisashi Utada. „A geomagnetic total intensity anomaly originated from lightning-induced isothermal remanent magnetization: case of the Yatsugatake Magnetic Observatory, central Japan“. Earth, Planets and Space 59, Nr. 3 (März 2007): 141–49. http://dx.doi.org/10.1186/bf03352687.

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