Journal articles: 'Ferromagnetism'

1

Kitagawa, Jiro, Masaki Fukuda, Satoshi Fukuda, Kenta Fujiki, Yuki Nakamura, and Terukazu Nishizaki. "Discovery of ferromagnetism in new multicomponent alloy Ti–Nb–Cr–Ru." APL Materials 10, no. 7 (July 1, 2022): 071101. http://dx.doi.org/10.1063/5.0097770.

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We report the discovery of ferromagnetism in the cubic CsCl-type Ti21∼25Nb20∼24Cr5∼10Ru∼49 multicomponent alloy. In metals, the appearance of ferromagnetism due to the Cr magnetic moment is a rare phenomenon. The purest sample shows ferromagnetism with the Curie temperature of 38 K. The effective magnetic moment and the Weiss temperature are 3.67 μ B/Cr and 58 K, respectively, derived from the temperature dependence of dc magnetization. These values mean the ferromagnetic exchange interaction between the localized Cr magnetic moments. The ferromagnetic nature is also confirmed by the isothermal magnetization curve with the highest magnetization of 1.1 μB/Cr at 2 K. The electronic structure calculation also supports a ferromagnetic ground state in the CsCl-type structure. We further investigated the effect of elemental substitution on the ferromagnetic behavior. The partial substitution of Pd for Ru heavily suppresses the Curie temperature, indicating that the Ru atom may play an essential role in sustaining ferromagnetism. Ti21∼25Nb20∼24Cr5∼10Ru∼49 would be the first example of the ferromagnetic Cr-containing multicomponent alloy, and this study shows the usefulness of the large compositional space in exploring novel phenomena.

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He, Wei, Lingling Kong, Weina Zhao, and Peng Yu. "Atomically Thin 2D van der Waals Magnetic Materials: Fabrications, Structure, Magnetic Properties and Applications." Coatings 12, no. 2 (January 21, 2022): 122. http://dx.doi.org/10.3390/coatings12020122.

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Two-dimensional (2D) van der Waals (vdW) magnetic materials are considered to be ideal candidates for the fabrication of spintronic devices because of their low dimensionality, allowing the quantization of electronic states and more degrees of freedom for device modulation. With the discovery of few-layer Cr2Ge2Te6 and monolayer CrI3 ferromagnets, the magnetism of 2D vdW materials is becoming a research focus in the fields of material science and physics. In theory, taking the Heisenberg model with finite-range exchange interactions as an example, low dimensionality and ferromagnetism are in competition. In other words, it is difficult for 2D materials to maintain their magnetism. However, the introduction of anisotropy in 2D magnetic materials enables the realization of long-range ferromagnetic order in atomically layered materials, which may offer new effective means for the design of 2D ferromagnets with high Curie temperature. Herein, current advances in the field of 2D vdW magnetic crystals, as well as intrinsic and induced ferromagnetism or antiferromagnetism, physical properties, device fabrication, and potential applications, are briefly summarized and discussed.

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Zhang, Yu Jun, Yuan Hua Lin, and Ce Wen Nan. "Annealing Temperature Dependent Ferromagnetic Behaviors Observed in Highly Orientated Pure NiO Thin Films." Key Engineering Materials 602-603 (March 2014): 956–59. http://dx.doi.org/10.4028/www.scientific.net/kem.602-603.956.

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Transition metal (TM) doped NiO is a promising candidate of p-type oxide diluted magnetic semiconductors (DMSs), which shows obvious room-temperature ferromagnetism. When researching the magnetic properties of DMSs, it is very important to get rid of ferromagnetic impurity phases by optimizing the preparation process. For this purpose, pure NiO thin films have been deposited by a pulsed laser deposition method and annealed by different annealing process. As-deposited or low-temperature annealed films show room-temperature ferromagnetism and high-temperature annealed films are not ferromagnetic. Nickel metal should be the origin of ferromagnetism in these thin films. On the other hand, high annealing temperature influences the microstructure of the film surface a lot. These results show a useful method to eliminate ferromagnetic impurity in NiO thin films and to optimize the preparation parameters of TM doped NiO thin films.

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Fang, D. N., X. Feng, and K. C. Hwang. "Study of magnetomechanical non-linear deformation of ferromagnetic materials: Theory and experiment." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, no. 12 (December 1, 2004): 1405–10. http://dx.doi.org/10.1243/0954406042690489.

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A robust constitutive model is desirable in order to guide the processing and development of ferromagnetism and for use in the design of ferromagnetic devices. In this paper, a non-linear constitutive model of soft ferromagnets is developed for general magnetomechanical loading histories. The experimental set-up and measured techniques, which were employed to measure the non-linear deformation of both the magnetostrictive materials and the soft ferromagnetic materials subjected to coupled magnetomechanical loading, are introduced. The general structure for the constitutive behaviour of ferromagnets including soft-ferromagnetic and hard-ferromagnetic materials is similar to the classical models of metal plasticity; i.e. a convex yield surface can be identified in a stress-magnetic field space, within which the deformation and magnetization are reversible, and increments of both remanent magnetization and remanent strains are normal to the yield surface. The state of materials is described in terms of the remanent strain and the remanent magnetization that are introduced as internal variables besides stress, strain, magnetic field and magnetization. The one-dimensional model is examined by numerical stimulations and the response of the ferromagnetic materials is discussed in comparison with the measured results. The macroscopic features of ferromagnets, such as hysteresis loop and magnetostrictive hysteresis, are predicted.

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Liao, Zhongxin, Tongtong Wang, Yonggang Liu, Baorui Xia, and Xingdong Jiang. "Ferromagnetic Cu3N Nanoparticles Demonstrated by X-ray Magnetic Circular Dichroism (XMCD) and the Density Functional Theory (DFT) Calculations." Journal of Nanoelectronics and Optoelectronics 15, no. 12 (December 1, 2020): 1494–501. http://dx.doi.org/10.1166/jno.2020.2892.

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In recent years, ferromagnetism induced by natural defects of nonmagnetic semiconductors has been widely investigated and expected to be applied in spintronics. On this basis, we report the ferromagnetic behavior of copper (I) nitride (Cu3N) nanoparticles. A robust room temperature ferromagnetism is found in Cu3N nanoparticles with the saturated magnetization of 4 memu/g (300 K). Based on the element-specific X-ray magnetic circular dichroism (XMCD) and the density functional theory (DFT) analysis, it is concluded that the ferromagnetism of Cu3N nanoparticles originate from the surface Cu vacancies. Moreover, by increasing the surface area of Cu3N, the variation of magnetism is realized, and the surface states related to ferromagnetism is further revealed.

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Cao, Ping, Yue Bai, and Zhi Qu. "The Structural, Electrical, Magnetic Properties of (Cu, Co) Co-Doped ZnO Thin Film." Applied Mechanics and Materials 556-562 (May 2014): 429–32. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.429.

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Successful synthesis of room-temperature ferromagnetic semiconductors, (Cu, Co) co-doped ZnO film is obtained by sol-gel method. It is found that the essential ingredient in achieving room-temperature ferromagnetism is Cu co-doping. By Hall-effect measurement ap-type conductivity was observed for the Cu co-doped films, which induced the room-temperature ferromagnetism.

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Yao, Minghai, Long Cheng, Shenglan Hao, Samir Salmanov, Mojca Otonicar, Frédéric Mazaleyrat, and Brahim Dkhil. "Great multiferroic properties in BiFeO₃/BaTiO₃ system with composite-like structure." Applied Physics Letters 122, no. 15 (April 10, 2023): 152904. http://dx.doi.org/10.1063/5.0139017.

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Multiferroic materials have attracted significant research attention due to their technological potential for applications as multifunctional devices. The scarcity of single-phase multiferroics and their low inherent coupling between multiferroic order parameters above room temperature pose a challenge to their further applications. We propose a 3BiFeO3/7BaTiO3 perovskite–perovskite composite that combines ferroelectricity and ferromagnetism. We demonstrate that the sintering temperature can tailor the ferroelectricity and ferromagnetism of the composites. The multiferroicity can be achieved at a low sintering temperature in the composite-like structure ceramics, and its multiferroic properties, especially the ferromagnetism, are superior to those of solid solutions. We also investigate the dynamic evolution of multiferroicity with sintering temperature. We adopt a nano–micro strategy to construct a composite-like microstructure, which results in optimized ferroelectric (1.62 μC cm−2) and ferromagnetic (0.16 emu/g) characteristics at a sintering temperature of 750 °C. We also found experimental evidence of the competition between antiferromagnetic and ferromagnetic interactions in the transition metal cation sublattice. Multiferroic BiFeO3/BaTiO3 composites with combined ferroelectric and ferromagnetic properties have significant potential for various applications.

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8

Singhal, R. K. "Room Temperature Ferromagnetism and its "Switch" Behaviour in some Dilute Magnetic Oxides: an Electronic Structure and Magnetization Study." Solid State Phenomena 171 (May 2011): 19–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.171.19.

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ZnO doped with a few per cent of magnetic ions such as Ni, Fe, Co exhibits room temperature ferromagnetism (RTFM), transforming it into a very promising candidate for future spintronic applications. Two samples i.e. ZnO doped with Ni and Cr (5% each) have been investigated in the present work. The samples were characterized by Rietveld refinement of X-ray diffraction (XRD) patterns and the superconducting quantum interference device (SQUID) magnetometry. Rietveld analysis confirms that both the polycrystalline samples possess wurtzite structure with no evidence of any secondary phase. The SQUID measurements exhibit a diamagnetic state for the pristine ZnO and a paramagnetic state for the as-synthesized (Cr and Ni)-doped ZnO samples. However, the post annealing in H2 and vacuum drive them to a remarkable ferromagnetic state at room temperature. No element specific signature for ferromagnetism was seen. Then the X-ray photoelectron spectroscopic (XPS) measurements were performed to investigate their electronic structure and exploring the origin of ferromagnetism in these diluted magnetic semiconductor materials. The XPS results confirm the creation of oxygen vacancies upon Hydrogen/ vacuum annealing, owned to the (Ni/Cr) 3d¬−O 2p hybridization. The findings suggest oxygen vacancies as the intrinsic origin for ferromagnetism in doped ZnO. The important feature of this work is that the ferromagnetism and the consequent electronic property changes are found to be reversible with regard to re-heating the samples in air, showing a switch “on” and “off” ferromagnetic ordering in the ZnO matrix.

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9

Correa, Marcio A., Armando Ferreira, Raphael M. Tromer, Leonardo D. Machado, Matheus Gamino, Sergio A. N. França Junior, Felipe Bohn, and Filipe Vaz. "Improving the Room-Temperature Ferromagnetism in ZnO and Low-Doped ZnO:Ag Films Using GLAD Sputtering." Materials 14, no. 18 (September 16, 2021): 5337. http://dx.doi.org/10.3390/ma14185337.

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ZnO and doped ZnO films with non-ferromagnetic metal have been widely used as biosensor elements. In these studies, the electrochemical measurements are explored, though the electrical impedance of the system. In this sense, the ferromagnetic properties of the material can be used for multifunctionalization of the sensor element using external magnetic fields during the measurements. Within this context, we investigate the room-temperature ferromagnetism in pure ZnO and Ag-doped ZnO films presenting zigzag-like columnar geometry. Specifically, we focus on the films’ structural and quasi-static magnetic properties and disclose that they evolve with the doping of low-Ag concentrations and the columnar geometry employed during the deposition. The magnetic characterization reveals ferromagnetic behavior at room temperature for all studied samples, including the pure ZnO one. By considering computational simulations, we address the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpret our results in terms of the Zn vacancy dynamics, its substitution by an Ag atom in the site, and the influence of the columnar geometry on the magnetic properties of the films. Our findings bring to light an exciting way to induce/explore the room-temperature ferromagnetism of a non-ferromagnetic metal-doped semiconductor as a promising candidate for biosensor applications.

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10

Nongkae, S., K. Tangphanit, S. Teeta, E. Swatsitang, and K. Wongsaprom. "Effect of argon annealing method on structural and ferromagnetic properties in Fe-doped SnO₂ powders." Journal of Physics: Conference Series 2145, no. 1 (December 1, 2021): 012031. http://dx.doi.org/10.1088/1742-6596/2145/1/012031.

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Abstract Nanocrystalline powders of Fe-doped SnO2 (Sn1-xFexO2) (x = 0.00, 0.01, 0.03, 0.05) were prepared by a hydrothermal method. The powders were calcined in argon atmosphere at 600 °C for 2 h, causing phase transition from diamagnetic and weak ferromagnetic behavior to a ferromagnetic state. No trace and other magnetic impurity phases was detected in the samples with Fe content up to 3%. The calcined samples of Fe-doped SnO2 revealed the room temperature ferromagnetism with highest magnetization values of 434.07 memu/g at 15 kOe for x = 0.05. The room temperature ferromagnetism of samples originated from oxygen vacancies that occurred in the argon calcination process. In particular, oxygen vacancy shows a significant role in ferromagnetic coupling corresponding to F-center interaction.

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11

Farkašovský, Pavol. "The Influence of Long-Range Hopping on Ferromagnetism in the Hubbard Model." International Journal of Modern Physics B 12, no. 07n08 (March 30, 1998): 803–8. http://dx.doi.org/10.1142/s0217979298000466.

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The phase diagram of the Hubbard model in an external magnetic field is examined by extrapolation of small-cluster exact-diagonalization calculations. Using a general expression for the hopping matrix elements (tij ~ q|i-j|) the influence of long-range hopping (band asymmetry) on ferromagnetism in this model is studied. It is found that the long-range hopping (nonzero q) stabilizes ferromagnetism in an external magnetic field for n > 1. In the opposite limit n≤1 the fully polarized ferromagnetic state is generally suppressed with increasing q. The critical value of magnetic field h below which the ferromagnetic state becomes unstable is calculated numerically.

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12

Huang, Pu, Peng Zhang, Shaogang Xu, Huide Wang, Xiuwen Zhang, and Han Zhang. "Recent advances in two-dimensional ferromagnetism: materials synthesis, physical properties and device applications." Nanoscale 12, no. 4 (2020): 2309–27. http://dx.doi.org/10.1039/c9nr08890c.

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13

FUKUMURA, TOMOTERU, YOSHINORI YAMADA, KAZUNORI UENO, HONGTAO YUAN, HIDEKAZU SHIMOTANI, YOSHIHIRO IWASA, LIN GU, SUSUMU TSUKIMOTO, YUICHI IKUHARA, and MASASHI KAWASAKI. "ELECTRON CARRIER-MEDIATED ROOM TEMPERATURE FERROMAGNETISM IN ANATASE (Ti,Co)O2." SPIN 02, no. 04 (December 2012): 1230005. http://dx.doi.org/10.1142/s2010324712300058.

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Since the discovery of room temperature ferromagnetism in ( Ti,Co ) O2 , the mechanism has been under discussion for a decade. Particularly, the central concern has been whether or not the ferromagnetic exchange interaction is mediated by charge carriers like ( Ga,Mn ) As . Recent two studies on the control of ferromagnetism in anatase ( Ti,Co ) O2 at room temperature via electric field effect [Y. Yamada et al., Science332, 1065 (2011)] and chemical doping [Y. Yamada et al., Appl. Phys. Lett.99, 242502 (2011)] indicate a principal role of electrons in the carrier-mediated exchange interaction. In this article, the authors review fundamental properties of anatase ( Ti,Co ) O2 and discuss the carrier mediated ferromagnetism.

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14

BHATT, R. N., and ERIK NIELSEN. "FERROMAGNETISM IN DOPED SEMICONDUCTORS WITHOUT MAGNETIC IONS." International Journal of Modern Physics B 22, no. 25n26 (October 20, 2008): 4595–606. http://dx.doi.org/10.1142/s0217979208050358.

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While ferromagnetism has been obtained above 100 K in doped semiconductors with magnetic ions such as Ga 1−x Mn x As , bulk doped semiconductors in the absence of magnetic ions have shown no tendency towards ferromagnetism. We re-examine the nonmagnetic doped semiconductor system at low carrier densities in terms of a generalized Hubbard model. Using exact diagonalization of the many-body Hamiltonian for finite clusters, we find that the system exhibits significant ferromagnetic tendencies at nanoscales, in a region of parameter space not accessible to bulk systems, but achievable in quantum dots and heterostructures. Implications for studying these effects in experimentally realizable systems, as well as the possibility of true (macroscopic) ferromagnetism in these systems is discussed.

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Zhou, Xiaocheng, Xu Sun, Zhuhua Zhang, and Wanlin Guo. "Ferromagnetism in a semiconducting Janus NbSe hydride monolayer." Journal of Materials Chemistry C 6, no. 36 (2018): 9675–81. http://dx.doi.org/10.1039/c8tc03016b.

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16

Habermeier, H. U., and G. Cristiani. "Ferromagnetic/Superconducting All-Oxide Superlattices." International Journal of Modern Physics B 17, no. 18n20 (August 10, 2003): 3729–31. http://dx.doi.org/10.1142/s0217979203021708.

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Superlattices consisting of ferromagnetic SrRuO 3 and superconducting YBa 2 Cu 3 O 7 [YBCO] layers of a thickness between 5 nm and 60 nm have been analyzed with respect to their magnetic [T mag ] as well superconducting [TC] ordering temperature. The reduction of both is compared with previous results obtained in YBCO / La 2/3 Ca 1/3 MnO 3 superlattices. Whereas the reduction of TC is comparable for both ferromagnetic materials the suppression of ferromagnetism is more pronounced in the case of the SrRuO 3-based superlattices. This result is discussed in terms of a competition of the order parameters giving rise to ferromagnetism and superconductivity and the role of interface roughness.

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17

Farkašovský, P. "Itinerant ferromagnetism in narrow-band metals." Condensed Matter Physics 24, no. 4 (2021): 42701. http://dx.doi.org/10.5488/cmp.24.42701.

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Since its introduction in 1963, the Hubbard model has becomes one of the most popular models used in the literature to study cooperative phenomena in narrow-band metals (ferromagnetism, metal-insulator transitions, charge-density waves, high-Tc superconductivity). Amongst all these cooperative phenomena, the problem of itinerant ferromagnetism in the Hubbard model has the longest history. However, in spite of an impressive research activity in the past, the underlying physics (microscopic mechanisms) that leads to the stabilization of itinerant ferromagnetism in Hubbard model (narrow-band metals) is still far from being understood. In this review we present our numerical results concerning this subject, which have been reached by small cluster exact diagonalization, density matrix renormalization group and quantum Monte Carlo calculations within various extensions of the Hubbard model. Particular attention is paid to a description of crucial mechanisms (interactions) that support the stabilization of the ferromagnetic state, and namely: (i) the long-range hopping, (ii) the correlated hopping, (iii) the long-range Coulomb interaction, (iv) the flat bands and (v) the lattice structure. Most of the presented results have been obtained for the one-dimensional case, but the influence of the increasing dimension of the system on the ferromagnetic state is also intensively discussed.

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Liu, Xiao Hua, Yan Fen Liu, Jing Hui Liu, Zhi Zhang Song, and Jian Jun Li. "Retarded Modes of Lateral Ferromagnetic/Ferromagnetic Superlattice." Applied Mechanics and Materials 151 (January 2012): 52–56. http://dx.doi.org/10.4028/www.scientific.net/amm.151.52.

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In this paper，we calculated the retarded modes of semi-infinite lateral ferromagnetic/ ferromagnetic superlattice with the effective medium theory. Take the Co/Ni system surface modes and bulk modes for the superlattice as the example and found some interesting properties which different from the lateral ferromagnetic/nonmagnetic superlattice. Lateral magnetism/magnetism superlattice have some complex retarded modes which are very common systems，changing the ratio of the superlattice ferromagnetism layer thickness so that two branches of surface modes frequency and bulk modes frequency band can be adjusted consequently. This tailoring effect is related to the two ferromagnetism layers saturation magnetization values. But the two saturation magnetization values are quite different than each other. If the difference between the tow values is large, the tailoring effect of f1 is more obvious. When the saturation magnetization value of the second ferromagnetic medium is approach to zero, this system will become magnetism/non-magnetism superlattice. If in Maxwell equation ε=0, the retarded modes will transite to ferromagnetic/ferromagnetic superlattice magnetostatic modes.

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19

SINGHAL, R. K., S. N. DOLIA, M. S. DHAWAN, S. K. GAUR, SUDHISH KUMAR, Y. T. XING, ELISA SAITOVITCH, and K. B. GARG. "ROOM TEMPERATURE FERROMAGNETISM IN Mn DOPED ZnO SEMICONDUCTOR." International Journal of Modern Physics B 23, no. 08 (March 30, 2009): 2029–40. http://dx.doi.org/10.1142/s0217979209052133.

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Following the theoretical prediction of ferromagnetism in Mn - and Co -doped ZnO , there has been an immense experimental search for dilute semiconductors that show ferromagnetic ordering above room temperature, and several workers have reported ferromagnetism in bulk samples as well as in thin films of these materials. Mn -doped ZnO is the key material in this regard, which has been, in the recent past, shown to exhibit such magnetic properties. Many more such attempts have either led to failure or to a much lower Tc, and there have been a lot of confronting reports casting considerable doubts on the magnetism in this system. In order to shed some light, we have prepared and characterized dilute Mn -doped (2 and 4%) ZnO pellets. SQUID measurements confirm that the 2% sample shows above room temperature ferromagnetic ordering, the ferromagnetic contribution coming mainly from the bulk. The ordering gets completely quenched for 4% Mn doping. Upon cooling down, the 2% Mn doped sample showed further enhancement in magnetic properties appreciably. On the other hand, the 4% sample did not show any ferromagnetic ordering, even down to 5 K, and has been found to retain the paramagnetic character.

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Sakon, Takuo, Yuhi Hayashi, Akihito Fukuya, Dexin Li, Fuminori Honda, Rie Umetsu, Xiao Xu, Gendo Oomi, Takeshi Kanomata, and Tetsujiro Eto. "Investigation of the Itinerant Electron Ferromagnetism of Ni2+xMnGa1−x and Co2VGa Heusler Alloys." Materials 12, no. 4 (February 14, 2019): 575. http://dx.doi.org/10.3390/ma12040575.

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Experimental investigations into the field dependence of magnetization and temperature dependences of magnetic susceptibility in Ni2+xMnGa1−x (x = 0.00, 0.02, 0.04) and Co2VGa Heusler alloy ferromagnets were performed following the spin fluctuation theory of itinerant ferromagnetism, called as “Takahashi theory”. We investigated the magnetic field dependence of magnetization at the Curie temperature TC, which is the critical temperature of the ferromagnetic–paramagnetic transition, and also at T = 5 K, which concerns the ground state of the ferromagnetic state. The field dependence of the magnetization was analyzed by means of the H vs. M5 dependence, and the field dependence of the ground state at 5 K was investigated by means of an Arrott plot (H/M vs. M2) according to the Takahashi theory. As for Ni2+xMnGa1−x, the spin fluctuation parameter in k-space (momentum space, TA) and that in energy space (T0) obtained at TC and 5 K were almost the same. On the contrary, as for Co2VGa, the H vs. M5 dependence was not shown at TC. We obtained TA and T0 by means of an Arrott plot at 5 K. We created a generalized Rhodes–Wohlfarth plot of peff/pS versus TC/T0 for the other ferromagnets. The plot indicated that the relationship between peff/pS and T0/TC followed Takahashi’s theory. We also discussed the spontaneous magnetic moment at the ground state, pS, which was obtained by an Arrott plot at 5 K and the high temperature magnetic moment, pC, at the paramagnetic phase. As for the localized ferromagnet, the pC/pS was 1. As for weak ferromagnets, the pC/pS was larger than 1. In contrast, the pC/pS was smaller than 1 by many Heusler alloys. This is a unique property of Heusler ferromagnets. Half-metallic ferromagnets of Co2VGa and Co2MnGa were in accordance with the generalized Rhodes–Wohlfarth plot with a km around 1.4. The magnetic properties of the itinerant electron of these two alloys appeared in the majority bands and was confirmed by Takahashi’s theory.

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Chambers, Scott A., and Robin F. C. Farrow. "New Possibilities for Ferromagnetic Semiconductors." MRS Bulletin 28, no. 10 (October 2003): 729–33. http://dx.doi.org/10.1557/mrs2003.214.

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AbstractNew candidate ferromagnetic semiconductors have recently been grown by doping semiconducting transition-metal oxides with magnetic impurities. Some of these exhibit ferromagnetism at and above room temperature. The critical question is why? In many cases, complex solid-state chemistry is involved in the synthesis and drives the resulting properties. The observation of room-temperature ferromagnetism in these materials must be accompanied by a careful identification of the phases and structures present in order to accurately identify the origin of the magnetism.

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ZHAO, GUO-MENG, and PIEDER BEELI. "NOVEL MAGNETIC PROPERTIES IN MULTI-WALLED CARBON NANOTUBE MATS: CONSISTENT WITH THE PARAMAGNETIC MEISSNER EFFECT DUE TO ULTRAHIGH-TEMPERATURE SUPERCONDUCTIVITY." International Journal of Modern Physics B 23, no. 20n21 (August 20, 2009): 4285–96. http://dx.doi.org/10.1142/s0217979209063444.

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We report magnetic measurements up to 1200 K on iron-contaminated multi-walled carbon nanotube mats with a Quantum Design vibrating sample magnetometer. Extensive magnetic data consistently show a ferrromagnetic transition at about 1000 K and a ferromagnetic-like transition at about 1275 K. The ferromagnetic transition at about 1000 K is associated with an Fe impurity phase and its saturation magnetization is in quantitative agreement with the Fe concentration measured by an inductively coupled plasma mass spectrometer. On the other hand, the saturation magnetization for the ferromagnetic-like phase (at 1275 K) is about four orders of magnitude larger than that expected from the measured concentration of Co or CoFe . We show that this ultrahigh-temperature ferromagnetic-like behavior cannot be explained by ferromagnetism of any Fe -carbon phases, carbon-based phases, or magnetic impurities, but is consistent with the paramagnetic Meissner effect (orbital ferromagnetism) due to the existence of π Josephson junctions in a granular superconductor.

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Yue, Zengji, Zhiqian Hou, Frank Yun, Peng Liu, Guangsai Yang, Abdulhakim Bake, Weiyao Zhao, et al. "Observation of itinerant ferromagnetism and coupled magnetoresistance in a spinel CuCo2S4." Journal of Materials Chemistry C 9, no. 28 (2021): 8874–81. http://dx.doi.org/10.1039/d1tc02065j.

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A novel ferromagnetic spinel CuCo₂S₄T_c ∼ 125 K was discovered. The ferromagnetism originates from Co and Cu atoms, and leads to a positive magnetoresistance in the paramagnetic regime, and a cross-over in the ferromagnetic regime.

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Straumal, Boris Borisovich, Svetlana G. Protasova, Andrei A. Mazilkin, Eberhard Goering, Gisela Schütz, Petr B. Straumal, and Brigitte Baretzky. "Ferromagnetic behaviour of ZnO: the role of grain boundaries." Beilstein Journal of Nanotechnology 7 (December 7, 2016): 1936–47. http://dx.doi.org/10.3762/bjnano.7.185.

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The possibility to attain ferromagnetic properties in transparent semiconductor oxides such as ZnO is very promising for future spintronic applications. We demonstrate in this review that ferromagnetism is not an intrinsic property of the ZnO crystalline lattice but is that of ZnO/ZnO grain boundaries. If a ZnO polycrystal contains enough grain boundaries, it can transform into the ferromagnetic state even without doping with “magnetic atoms” such as Mn, Co, Fe or Ni. However, such doping facilitates the appearance of ferromagnetism in ZnO. It increases the saturation magnetisation and decreases the critical amount of grain boundaries needed for FM. A drastic increase of the total solubility of dopants in ZnO with decreasing grain size has been also observed. It is explained by the multilayer grain boundary segregation.

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Wang, Huan, Xi Chen, Xing Yuan Chen, and Yu Jun Zhao. "Stable Antiferromagnetism of Orthorhombic BiCrO₃ under Pressure: a Theoretical Study." Advanced Materials Research 298 (July 2011): 243–48. http://dx.doi.org/10.4028/www.scientific.net/amr.298.243.

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The realization of ferromagnetism or ferrimagnetism in BiCrO3 is crucial for its potential application in magnetoelectronic devices. It is known from experiment that the antiferromagnetic monoclinic phase of BiCrO3 transits to orthorhombic as pressure beyond 1GPa. Here, we present a first-principles study of the magnetism of orthorhombic BiCrO3 under pressures up to 80GPa. We find that the energy difference between its ferromagnetic phase and the ground state of G-type anti-ferromagnetic phase becomes greater as the pressure increases, as well as the estimated magnetic transition temperature TN. This implies the difficulty of transforming BiCrO3 into ferromagnetism by external pressure, and thus other approaches (such as doping magnetic ions) are necessary to explore its potential application in magnetoelectronic devices.

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KOO, JE HUAN, and GUANGSUP CHO. "METALLIC FERROMAGNETISM DRIVEN BY PHONON-ENHANCED SPIN FLUCTUATIONS." International Journal of Modern Physics B 21, no. 06 (March 10, 2007): 857–69. http://dx.doi.org/10.1142/s021797920703676x.

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We investigate the metallic ferromagnetism for materials with incomplete 3d-orbitals. The ferromagnetism occurs in electrons of s-orbitals by phonon-enhanced spin flippings of d-electrons via s-d exchange interactions, which was discussed by us [Phys. Rev. B61, 4289 (2000)]. We know the electron-electron interaction, U sd , mediated by phonon-enhanced spin flippings is repulsive for metallic ferromagnetic materials but attractive for high transition temperature superconductors (HTSC). The electron-electron interaction, U sd , is an order of magnitude stronger than that by Kondo-type bare spin-flippings. We elucidate non-occurrence of ferromagnetism in Pd even though it has very strong exchange interactions. We also show that the charge sum rule is recovered in the case of inclusion of U sd . We calculate the resistivity in normal states.

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27

Sun, Y., W. Tong, and X. Luo. "Possible magnetic correlation above the ferromagnetic phase transition temperature in Cr2Ge2Te6." Physical Chemistry Chemical Physics 21, no. 45 (2019): 25220–25. http://dx.doi.org/10.1039/c9cp04685b.

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CHOI, HEON-JIN, HAN-KYU SEONG, and UNGKIL KIM. "DILUTED MAGNETIC SEMICONDUCTOR NANOWIRES." Nano 03, no. 01 (February 2008): 1–19. http://dx.doi.org/10.1142/s1793292008000848.

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An idea for simultaneously manipulating spin and charge in a single semiconductor medium has resulted in the development of diluted magnetic semiconductors (DMSs), which exhibits surprisingly room temperature ferromagnetic signatures despite having controversial ferromagnetic origin. However, achievement of truly room temperature ferromagnetism by carrier mediation is still the subject of intense research to develop the practical spin-based devices. Nanowires with one-dimensional nanostructure, which offers thermodynamically stable features and typically single crystalline and defect free, have a number of advantages over thin films with respect to studying ferromagnetism in DMSs. This review focuses primarily on our works on GaN -based DMS nanowires, i.e., Mn -doped GaN , Mn -doped AlGaN and Cu -doped GaN nanowires. These DMS nanowires have room temperature ferromagnetism by the local magnetic moment of doping elements that are in a divalent state and in tetrahedral coordination, thus substituting Ga in the wurtzite-type network structure of host materials. Importantly, our evidences indicate that the magnetism is originated from the ferromagnetic interaction driven by the carrier. These outcomes suggest that nanowires are ideal building blocks to address the magnetism in DMS due to their thermodynamic stability, single crystallinity, free of defects and free standing nature from substrate. Nanowires themselves are ideal building blocks for nanodevices and, thus, it would also be helpful in developing DMS-based spin devices.

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Seo, Junho, Duck Young Kim, Eun Su An, Kyoo Kim, Gi-Yeop Kim, Soo-Yoon Hwang, Dong Wook Kim, et al. "Nearly room temperature ferromagnetism in a magnetic metal-rich van der Waals metal." Science Advances 6, no. 3 (January 2020): eaay8912. http://dx.doi.org/10.1126/sciadv.aay8912.

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In spintronics, two-dimensional van der Waals crystals constitute a most promising material class for long-distance spin transport or effective spin manipulation at room temperature. To realize all-vdW-material–based spintronic devices, however, vdW materials with itinerant ferromagnetism at room temperature are needed for spin current generation and thereby serve as an effective spin source. We report theoretical design and experimental realization of a iron-based vdW material, Fe4GeTe2, showing a nearly room temperature ferromagnetic order, together with a large magnetization and high conductivity. These properties are well retained even in cleaved crystals down to seven layers, with notable improvement in perpendicular magnetic anisotropy. Our findings highlight Fe4GeTe2 and its nanometer-thick crystals as a promising candidate for spin source operation at nearly room temperature and hold promise to further increase Tc in vdW ferromagnets by theory-guided material discovery.

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30

Rajan, K. Jayanthi, Kausalya Ganesan, Satyanaryana Lanka, Swati Bishnoi, and Manorama V. Sunkara. "Probing high temperature ferromagnetism and its paramagnetic phase change due to Eu3+ incorporation in ZnO nanophosphors." RSC Advances 6, no. 79 (2016): 75669–80. http://dx.doi.org/10.1039/c6ra10853a.

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Ferromagnetic oxide semiconductors exhibiting efficient luminescent properties together with robust ferromagnetism above room temperature form an exclusive class of spintronic materials endowed with both charge and spin degrees of freedom.

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31

Ham, M. H., Min Chang Jeong, W. Y. Lee, Jae Min Myoung, J. M. Lee, J. Y. Chang, and S. H. Han. "Magnetotransport in Ferromagnetic (Ga,Mn)N Epitaxial Films." Materials Science Forum 449-452 (March 2004): 1041–44. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.1041.

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We present the ferromagnetism and magnetotransport properties in the (Ga,Mn)N epitaxial films with very low Mn concentrations grown by plasma-enhanced molecular beam epitaxy (PEMBE). The (Ga,Mn)N epitaxial films were found to exhibit ferromagnetic ordering with Curie temperature of 700 K. All the films exhibit n-type characteristics. The negative magnetoresistance was observed below 150 K, and found to gradually increase with decreasing temperature. The ferromagnetism in the (Ga,Mn)N is due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the localized Mn moments mediated by the electron gas.

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32

NOZUE, Y., T. KODAIRA, S. OHWASHI, N. TOGASHI, and O. TERASAKI. "FERROMAGNETISM OF ALKALI-METAL CLUSTERS INCORPORATED IN THE PERIODIC SPACE OF ZEOLITE LTA." Surface Review and Letters 03, no. 01 (February 1996): 701–6. http://dx.doi.org/10.1142/s0218625x96001261.

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Magnetic properties are reported for rubidium and potassium clusters arrayed in a simple-cubic structure in zeolite LTA crystal. A ferromagnetism is observed, although no magnetic element is contained there. The result clearly indicates the intercluster interaction. The ferromagnetic properties vary depending on the average number of ns electrons of cluster. Optical properties reveal quantum electronic levels of cluster. The ferromagnetism is interpreted qualitatively in terms of the itinerant electron model based on the quantum levels of cluster. The magnetic properties of various clusters observed in zeolites are discussed from the microscopic point of view.

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33

HAN, Y. P., X. J. WANG, Q. R. HOU, Q. W. WANG, and J. X. WANG. "MAGNETIC PROPERTIES OF Fe0.95Co0.05Si2 SEMICONDUCTING FILM." Modern Physics Letters B 26, no. 15 (May 17, 2012): 1250097. http://dx.doi.org/10.1142/s0217984912500972.

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The Fe 0.95 Co 0.05 Si 2 semiconducting film has been successfully grown on glass substrate by magnetron sputtering at substrate temperature of 637 K and then thermal annealing at 823 K for one hour in high vacuum. The Raman data and high Seebeck coefficient suggested that the β- Fe 0.95 Co 0.05 Si 2 semiconducting film was achieved. Room temperature ferromagnetism was observed, and the ferromagnetic phase transition was at about 380 K. The possible reason for the ferromagnetism of the β- Fe 0.95 Co 0.05 Si 2 semiconducting film was discussed.

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34

LIU, GUANG-HUA, HAI-LONG WANG, and GUANG-SHAN TIAN. "LONG-RANGE ELECTRON HOPPING AND FERROMAGNETISM IN CLUSTERS." International Journal of Modern Physics B 25, no. 06 (March 10, 2011): 747–56. http://dx.doi.org/10.1142/s0217979211058225.

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In the present paper, we investigate the frustration effect caused by the long-range electron hopping on ferromagnetism in atomic or molecular clusters. First, for an idealized Hubbard model with constant electron hopping amplitude, we prove rigorously that interplay between such frustration effect and the on-site Coulomb interaction produces the saturated ferromagnetism when the cluster is slightly doped with electron. Then, by exact diagonalization calculation, we study some more realistic clusters and show that the ferromagnetic ground state is still stable as long as the Coulomb repulsion interaction between electrons is sufficiently strong.

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35

Cao, Ping, Yue Bai, and Zhi Qu. "The Room Temperature Ferromagnetism of (N, Co) Co-Doped ZnO Nanopaticles." Applied Mechanics and Materials 577 (July 2014): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amm.577.19.

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Co-doped ZnO nanoparticles were fabricated by an electrodeposition method. The XPS results show Co ions have doped into the ZnO crystal lattices successfully. The as-grown sample has no ferromagnetism at room temperature. But after an ammine plasma treatment the room temperature ferromagnetism were detected on Co0.04Zn0.96O nanoparticles. The Hall measurement reveals after the treatment the resistivity increase by three orders of magnitude. Although the aspect conductivity is n type, some holes generated by N doping play an important role to induce the ferromagnetic properties for Co doped ZnO sample.

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Meng, Xu Dong, Fu Yang, and Xiao Yu Liu. "The Magnetic Ordering of SiCN Films Prepared by Ion Implantation." Key Engineering Materials 531-532 (December 2012): 325–28. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.325.

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Room-temperature ferromagnetism was observed in the SiCN films prepared by ion implantation. The result indicates that N ion implantation dosage in the film has great effect on the observed room-temperature ferromagnetism of the films. Along with the increase of ion implantation dosage, the N ions increase and the magnetism enhances. Because of the ion implantation will cause a lot of defects on the surface of SiC films, which will induce a lot of vacancies. The C atoms are replaced by the N ions doped, the concentration of the N ions decides the charges states and spin polarizations of Si vacancy defects. Local magnetic moment is induced because of the spin polarization of the Si vacancy defects, and the films show ferromagnetic properties.Charge states and spin polarizations of silicon vacancy defects can be manipulated by N atoms which induces the ferromagnetism.

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37

Cheng, Bin, Hongwei Qin, Zhongli Zhang, Weikang Liu, Tingting Miao, Jihao Xie, Liang Liu, Guangjun Zhou, and Jifan Hu. "Electric-field control of magnetic properties for amorphous Fe2O3/LiTaO3thin film." Journal of Materials Chemistry C 6, no. 43 (2018): 11608–14. http://dx.doi.org/10.1039/c8tc02588f.

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Amorphous-Fe₂O₃/LiTaO₃film can exhibit weak ferromagnetism, which may arise from some inhomogeneous, non-collinear, ferromagnetic ordered clusters with short range order.

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38

Meng, Dechao, Hongli Guo, Zhangzhang Cui, Chao Ma, Jin Zhao, Jiangbo Lu, Hui Xu, et al. "Strain-induced high-temperature perovskite ferromagnetic insulator." Proceedings of the National Academy of Sciences 115, no. 12 (March 5, 2018): 2873–77. http://dx.doi.org/10.1073/pnas.1707817115.

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Ferromagnetic insulators are required for many new magnetic devices, such as dissipationless quantum-spintronic devices, magnetic tunneling junctions, etc. Ferromagnetic insulators with a high Curie temperature and a high-symmetry structure are critical integration with common single-crystalline oxide films or substrates. So far, the commonly used ferromagnetic insulators mostly possess low-symmetry structures associated with a poor growth quality and widespread properties. The few known high-symmetry materials either have extremely low Curie temperatures (≤16 K), or require chemical doping of an otherwise antiferromagnetic matrix. Here we present compelling evidence that the LaCoO3 single-crystalline thin film under tensile strain is a rare undoped perovskite ferromagnetic insulator with a remarkably high TC of up to 90 K. Both experiments and first-principles calculations demonstrate tensile-strain–induced ferromagnetism which does not exist in bulk LaCoO3. The ferromagnetism is strongest within a nearly stoichiometric structure, disappearing when the Co2+ defect concentration reaches about 10%. Significant impact of the research includes demonstration of a strain-induced high-temperature ferromagnetic insulator, successful elevation of the transition over the liquid-nitrogen temperature, and high potential for integration into large-area device fabrication processes.

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39

Abragam, Anatole. "Nuclear ferromagnetism and ant ferromagnetism." Contemporary Physics 33, no. 5 (September 1992): 305–12. http://dx.doi.org/10.1080/00107519208223980.

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40

Gao, Xing Guo, Bao Yuan Man, Mei Liu, Cheng Yang, Chuan Song Chen, Zhen Cui Sun, and Shi Cai Xu. "Intrinsic Ferromagnetism of the GaMnN Thin Films." Advanced Materials Research 629 (December 2012): 49–54. http://dx.doi.org/10.4028/www.scientific.net/amr.629.49.

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The Mn-doped GaN (GaMnN) films on c-plane sapphire substrates were prepared by using Laser Molecular Beam Epitaxy (LMBE) at different base nitrogen pressure, followed by annealing in the ammonia atmosphere at 950 °C for 30 min, to study the original reason of the room-temperature ferromagnetism of GaMnN films. We found the crystalline quality was sensitive to the base nitrogen pressure during growth. X-ray photoelectron spectra (XPS) analysis confirmed that the Mn3+ and Mn2+ coexist in our samples. The room-temperature ferromagnetic behavior can be explained by double exchange. The ferromagnetism would be weakened by the nitrogen vacancies, which plays a role of donor.

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41

Murata, Takeshi, Tomoyuki Terai, Takashi Fukuda, and Tomoyuki Kakeshita. "Magnetic Phase Diagram in Layered Perovskite Manganite La_2-2xSr_1+2xMn₂O₇ (0.313≤x≤0.350)." Materials Science Forum 512 (April 2006): 183–88. http://dx.doi.org/10.4028/www.scientific.net/msf.512.183.

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We have measured the magnetization as a function of temperature and magnetic field in layered perovskite manganites of La2-2xSr1+2xMn2O7 single crystals (x=0.313, 0.315, 0.320, 0.350) in order to know their magnetic structures. All the present manganites exhibit magnetic transitions from ferromagnetic to paramagnetic at 76K, 107K, 120K and 125K for x=0.313, 0.315, 0.320 and 0.350, respectively. For x=0.350 and 0.320, the magnetic structure is a planar ferromagnetism whose easy axis is in the ab-plane at all temperatures below the Curie temperature. On the other hand, for x=0.315 and 0.313, the magnetic structure is an uniaxial ferromagnetism whose easy axis is along the c-axis below 85K and 66K, respectively, and a planar ferromagnetism above the temperature. From the results described above, we made the detailed magnetic phase diagram of layered perovskite manganite La2-2xSr1+2xMn2O7 (0.313≤x≤0.350).

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42

Cao, Ming He, Jun Yuan, and Jun Jiang. "Study of the Weak Ferromagnetism in Ca_1-xLa_xB₆ Ceramics." Materials Science Forum 475-479 (January 2005): 1173–76. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1173.

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Ferromagnetism in La-doped single crystal CaB6 is interesting because it has no partially filled d- or f- orbits in CaB6. In this paper, we have investigated the relationship between the ferromagnetic properties with the La content in CaB6 polycrystalline ceramics prepared by redox method. Contrary to the single crystal results, we found that there is no direct correlation with the level of La substitution in ceramics samples Ca1-xLaxB6 (0 £ x £ 0.03). Instead we have shown that it is related to Fe impurities. Our results show it is important to consider the magnetic impurities in discussing the weak ferromagnetism in borides.

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43

Liu, W. J., X. D. Tang, Z. Tang, W. Bai, and N. Y. Tang. "Oxygen Defects Mediated Magnetism of Ni Doped ZnO." Advances in Condensed Matter Physics 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/424398.

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Ni doped ZnO nanoparticles were synthesized by a solution route and annealed in O2, air, and Ar, respectively. X-ray diffraction and X-ray photoelectron spectroscopy measurements show that the samples possess typical wurtzite structure and have no other impurity phases. Magnetization loops for ZnO samples were measured and clearly show typical ferromagnetic saturation behavior. With the defect analysis based on photoluminescence spectroscopy, the effect of defects on the nature and origin of ferromagnetism was investigated. The results suggest that oxygen vacancies, especially single ionized oxygen vacancies, play a crucial role in mediating ferromagnetism in the Ni doped ZnO.

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SOUMA, SATOFUMI, SEUNG JOO LEE, and TAE WON KANG. "NUMERICAL STUDY OF FERROMAGNETISM IN DILUTED MAGNETIC SEMICONDUCTOR QUANTUM-WELLS." International Journal of Modern Physics B 19, no. 19 (July 30, 2005): 3151–60. http://dx.doi.org/10.1142/s0217979205031973.

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We study the ferromagnetism in III-V diluted magnetic semiconductor (DMS) quantum-wells theoretically and numerically taking into account the occupation of multiple subbands by holes in quantum wells. Starting from the mean-field theory of carrier-induced ferromagnetism in III-V DMS along with the exchange-correlation interaction of holes within the local spin density approximation, we found that the ferromagnetic transition temperature Tc of DMS quantum-wells exhibits step-function-like dependence on the hole density, reflecting the quasi-two-dimensional nature of systems. Moreover, the temperature dependence of the spin polarization shows quite distinct characteristics depending on the hole density.

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45

Zhao, Xingbin, Li Li, Kuo Bao, Pinwen Zhu, Qiang Tao, Shuailing Ma, Bo Liu, Yufei Ge, Da Li, and Tian Cui. "Synthesis and characterization of a strong ferromagnetic and high hardness intermetallic compound Fe2B." Physical Chemistry Chemical Physics 22, no. 46 (2020): 27425–32. http://dx.doi.org/10.1039/d0cp03380d.

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Fe₂B is a promising strong ferromagnetic material with high hardness, which makes it a good candidate for multifunction applications in a harsh environment. This work bridges the chasm between strong ferromagnetism and high hardness communities.

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46

Kahal, L. "Half-metallic ferromagnetism and band gap reduction in Cu-doped zinc-blende BeO: first-principle study -=SUP=-*-=/SUP=-." Физика твердого тела 59, no. 5 (2017): 835. http://dx.doi.org/10.21883/ftt.2017.05.44367.337.

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In this paper, we report ferromagnetism in copper doped zinc-blende BeO. Our first-principles calculations based on spin density functional theory predicts a total magnetic moment of 1 muB per copper when copper substitutes beryllium in BeO, where 0.58 muB is localized at Cu atom. The results obtained show that the ferromagnetic state is 34 meV lower than the antiferromagnetic state. Calculations indicate an appreciable band gap reduction in BeO. The analysis of the partial density of states reveals that ferromagnetism and reduction of BeO band gap are principally due to the strong p-d coupling of O and Cu. DOI: 10.21883/FTT.2017.05.44367.337

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47

Troyanchuk, I. O., M. V. Bushinsky, V. Efimov, S. Schorr, C. Ritter, and V. Sikolenko. "Ferromagnetic ordering in La0.7Sr0.3Mn3+0.85Nb5+0.15O3 manganite." Powder Diffraction 30, S1 (May 5, 2015): S97—S100. http://dx.doi.org/10.1017/s0885715615000032.

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Structural measurements have been performed on the La0.7Sr0.3Mn3+0.85Nb5+0.15O3 compound with oxidation state of manganese close to +3. The composition undergoes a structural transition from rhombohedral to orthorhombic symmetry below room temperature. The calculated structural parameters show that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The compound is ferromagnetic with a Curie point of around 150 K and a magnetic moment of 3.1 μB/Mn. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder leads to suppression of ferromagnetism.

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Karchev, N. I., K. B. Blagoev, K. S. Bedell, and P. B. Littlewood. "Coexistence of Superconductivity and Ferromagnetism in Ferromagnetic Metals." Physical Review Letters 86, no. 5 (January 29, 2001): 846–49. http://dx.doi.org/10.1103/physrevlett.86.846.

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Patel, Rajen, and Frank J. Owens. "Evidence for Stable High-Temperature Ferromagnetism in Fluorine-Treated C60." Journal of Materials 2013 (February 2, 2013): 1–5. http://dx.doi.org/10.1155/2013/261304.

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It is shown by magnetic field dependent ac susceptibility, magnetic force microscopy, and ferromagnetic resonance that exposure of C60 to fluorine at 160°C produces a stable ferromagnetic material with a Curie temperature well above room temperature. The exposure to fluorine is accomplished by decomposing a fluorine-rich polymer, trifluorochloroethylene [F2C–CFCl]n, which has C60 imbedded in it. Based on previous experimental observations and molecular orbital calculations, it is suggested that the ferromagnetism is arising from crystals of C60–F.

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Wu, Jin, Ke Yu, Yongsheng Zhang, Lijun Li, and Ziqiang Zhu. "Synthesis and room-temperature ferromagnetism of cobalt-doped SnO2 nanowires." Journal of Materials Research 24, no. 6 (June 2009): 2001–5. http://dx.doi.org/10.1557/jmr.2009.0236.

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We have observed ferromagnetism in dilute cobalt-doped SnO2 nanowires at room temperatures. The Co-doped SnO2 nanowires with an average diameter of ∼50 nm were synthesized by the thermal chemical vapor transport method. High-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy analyses demonstrate that the nanowires are single-crystal structures and Co is homogeneously doped into the SnO2 lattice. The ferromagnetic hysteresis curves and temperature-dependent magnetization measurement provide evidence for ferromagnetic properties with a Curie temperature above room temperature. Oxygen annealing has been performed to study the roles played by the oxygen vacancies in determining the ferromagnetic properties of the nanowires.

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Journal articles on the topic 'Ferromagnetism'

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