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Journal articles on the topic 'Ferromagnetisme'

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Published: 4 June 2021
Last updated: 25 January 2025

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1

Gilman, J. J. "Enthusiasms and Realities in Advanced Materials." MRS Bulletin 12, no. 8 (December 1987): 50–53. http://dx.doi.org/10.1557/s0883769400066781.

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Tom Read arrived at Columbia University on the same day that I did in 1948. He was a new professor in the School of Mines and I was a new graduate student. He was more than just a new professor. He was exceptional for that time. His father, T.T. Read, had been famous as an archeological metallurgist and professor at Columbia when the School of Mines was the premier school of its kind in the country. A measure of its eminence is that Irving Langmuir chose to study there rather than in a standard chemistry department.The younger Tom Read had studied physics at Columbia under Shirley Quimby, one of the few solid-state physics professors of the time (pre-transistor). After graduation he worked at the Frankford Arsenal and at the Westinghouse Research Laboratories, where he and Frederick Seitz wrote their definitive review of the mechanisms of the plastic deformation of solids.When he came back to Columbia as a professor, Tom Read's physics background made him almost unique among metallurgy professors. And, he had the zeal of a crusader — he was determined to teach fundamental knowledge rather than recipes. His techniques were often novel.For example, one semester we were to learn about ferromagnetism. But he had trouble finding a good American text, so he announced that we would study both ferromagnetism and German using the famous book by Becker and Doring called Ferromagnetisms. As a result, I have never forgotten the essentials of ferromagnetism.
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2

Elesin, Vladimir F., V. V. Kapaev, and Yurii V. Kopaev. "Coexistence of ferromagnetism and nonuniform superconductivity." Uspekhi Fizicheskih Nauk 174, no. 9 (2004): 1017. http://dx.doi.org/10.3367/ufnr.0174.200409h.1017.

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3

ZHU, ZHONG HUA, DA QIANG GAO, ZHAO LONG YANG, JING ZHANG, ZHEN HUA SHI, ZHI PENG ZHANG, and DE SHENG XUE. "SIZE-DEPENDENT FERROMAGNETISM AND ITS AGING BEHAVIOR IN PURE Y2O3 NANOPARTICLES." Modern Physics Letters B 27, no. 05 (February 5, 2013): 1350031. http://dx.doi.org/10.1142/s0217984913500310.

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A series of Y 2 O 3 nanoparticles of average particle size 19–37 nm are synthesized by a glycine-nitrate method. Room temperature ferromagnetism is observed in all samples. The magnetization of these samples decreases with increasing annealing temperature, showing a size-dependent ferromagnetism. Vacuum-heating effect on the ferromagnetism is also investigated, which indicates that the observed ferromagnetism is possibly associated with oxygen defects. Interestingly, an aging behavior of the ferromagnetism is observed when the sample is exposed to air or immersed in ethanol. These results further support the oxygen-vacancy-mediated ferromagnetism mechanism.
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4

Gulacsi, M., G. Kovacs, and Z. Gulacsi. "An extension to flat band ferromagnetism." Modern Physics Letters B 28, no. 28 (November 10, 2014): 1450220. http://dx.doi.org/10.1142/s0217984914502200.

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From flat band ferromagnetism, we learned that the lowest energy half-filled flat band gives always ferromagnetism if the localized Wannier states on the flat band satisfy the connectivity condition. If the connectivity conditions are not satisfied, ferromagnetism does not appear. We show that this is not always the case namely, we show that ferromagnetism due to flat bands can appear even if the connectivity condition does not hold due to a peculiar behavior of the band situated just above the flat band.
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5

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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6

Hu, P., S. X. Wu, and S. W. Li. "Enhancement of room-temperature ferromagnetism in manganese oxide thin films grown on Nb:SrTiO3 substrates." Modern Physics Letters B 28, no. 20 (August 10, 2014): 1450162. http://dx.doi.org/10.1142/s0217984914501620.

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In this paper, α- Mn 2 O 3 thin films were fabricated by plasma-assisted molecular beam epitaxy on SrTiO 3 and Nb : SrTiO 3, respectively. The grown samples showed room temperature ferromagnetism (RFM) properties. All the experimental results manifested that the RFM properties in undoped thin films were induced by oxygen vacancies formed during the growth process. Even more, the ferromagnetism of thin films grown on Nb : SrTiO 3 were enhanced, and these results confirmed the fact that oxygen vacancies induced ferromagnetism. That is to say, more oxygen vacancies result the more unpaired electrons induced prominent abnormal spin causing ferromagnetism.
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7

Shin, Jaemin, Tyafur Pathan, Guanyu Zhou, and Christopher L. Hinkle. "(Invited) Bulk Traps in Layered 2D Gate Dielectrics." ECS Meeting Abstracts MA2024-01, no. 21 (August 9, 2024): 1291. http://dx.doi.org/10.1149/ma2024-01211291mtgabs.

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Ultra-thin ferromagnets, when coupled with magnetoelectric or multiferroic materials, could potentially enable highly energy-efficient electric field control of the magnet for use in nanoelectronic memories. Substitutional doping of magnetic impurities in monolayer transition metal dichalcogenides (TMDs) may be a promising way to create 2D ferromagnets but, according to theoretical calculations, require high doping levels (10-20 %) to achieve above room temperature (RT) Curie temperature. Room-temperature ferromagnetism has been reported for very low doping levels (0.1-1%), in conflict with the theoretical calculations, and always in the presence of high concentrations of defects, making it unclear if the dopants alone are responsible for this ferromagnetism. In this work, we use a combination of molecular beam epitaxy (MBE), plan-view TEM, XRD, XPS, Raman, and magnetometry to study iron and vanadium doping in monolayer WSe2. We show that optimally grown monolayers with up to 35% doping and low defect density show no ferromagnetism. Interestingly, ferromagnetism is observed when these monolayers contain a significant amount of selenium vacancies (Sevac), intentionally created via a post-growth heat treatment process, and magnetism is seen to scale with heating time/vacancy concentration. Moreover, even undoped WSe2 shows similar ferromagnetism for Sevac > 1014 cm-2. This ferromagnetism can later be quenched by filling these vacancies via Se annealing. For films with low Se vacancy concentration, TEM analysis reveals significant clustering of the V and Fe dopants which likely suppresses the ferromagnetism predicted by theory - a problem that has previously plagued III-V based dilute magnetic semiconductors as well. We go so far as to claim that all of the above room-temperature ferromagnetism reports in the literature thus far are due to Se vacancies and not magnetic doping.
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8

Walter, Jeff, Bryan Voigt, Ezra Day-Roberts, Kei Heltemes, Rafael M. Fernandes, Turan Birol, and Chris Leighton. "Voltage-induced ferromagnetism in a diamagnet." Science Advances 6, no. 31 (July 2020): eabb7721. http://dx.doi.org/10.1126/sciadv.abb7721.

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Increasingly impressive demonstrations of voltage-controlled magnetism have been achieved recently, highlighting potential for low-power data processing and storage. Magnetoionic approaches appear particularly promising, electrolytes and ionic conductors being capable of on/off control of ferromagnetism and tuning of magnetic anisotropy. A clear limitation, however, is that these devices either electrically tune a known ferromagnet or electrically induce ferromagnetism from another magnetic state, e.g., antiferromagnetic. Here, we demonstrate that ferromagnetism can be voltage-induced even from a diamagnetic (zero-spin) state suggesting that useful magnetic phases could be electrically induced in “nonmagnetic” materials. We use ionic liquid–gated diamagnetic FeS2 as a model system, showing that as little as 1 V induces a reversible insulator-metal transition by electrostatic surface inversion. Anomalous Hall measurements then reveal electrically tunable surface ferromagnetism at up to 25 K. Density functional theory–based modeling explains this in terms of Stoner ferromagnetism induced via filling of a narrow eg band.
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9

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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10

Rasaili, Prithivi, Nitin Kumar Sharma, and Ajaya Bhattarai. "Comparison of Ferromagnetic Materials: Past Work, Recent Trends, and Applications." Condensed Matter 7, no. 1 (January 24, 2022): 12. http://dx.doi.org/10.3390/condmat7010012.

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Despite our traditional concept-based understanding of ferromagnetism, an investigation of this phenomenon has revealed several other facts. Ferromagnetism was previously supposed to be exhibited by only a few elements. Subsequently, it was realized that specific elements with d- or f- orbitals demonstrated this phenomenon. When elements without these orbitals exhibited ferromagnetism, intrinsic origin-based and structural defect-based theories were introduced. At present, nonmagnetic oxides, hexaborides of alkaline-earth metals, carbon structures, and nonmetallic non-oxide compounds are gaining significant attention owing to their potential applications in spintronics, electronics, biomedicine, etc. Therefore, herein, previous work, recent trends, and the applications of these materials and studies based on relevant topics, ranging from the traditional understanding of ferromagnetism to the most recent two-element-based systems, are reviewed.
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11

Spires, D. A. Xiaolin. "Ferromagnetism." Nature 562, no. 7727 (October 2018): 454. http://dx.doi.org/10.1038/d41586-018-07050-4.

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12

Coey, J. M. D. "ferromagnetism." Solid State Sciences 7, no. 6 (June 2005): 660–67. http://dx.doi.org/10.1016/j.solidstatesciences.2004.11.012.

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13

Kato, Yusuke, Hiroto Ohta, and Hiroko Aruga Katori. "Magnetic Study on Y2M3Co9P7 (M: Transition Metals) with Cation-Ordered Zr2Fe12P7-Type Structure." Solid State Phenomena 289 (April 2019): 164–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.289.164.

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We successfully synthesized polycrystalline samples of Y2M3Co9P7 (M = Cr, Mn, Fe, Co, Mo, and Ru), which has the Zr2Fe12P7-type hexagonal structure with M and Co selectively occupy the pyramidal site and three tetrahedral ones, respectively. For the case of M = Co, or Y2Co12P7, the itinerant electronic ferromagnetism was observed below the Curie temperature TC = 153 K. For M = Cr, Mn, Fe, and Ru, the ferromagnetism was also observed below TC = 167 K, 229 K, 233 K and 18 K, respectively, whereas for M = Mo, an exchange-enhanced Pauli paramagnetism tool the place of the ferromagnetism. Among compounds with M being 3d transition metals, TC and spontaneous magnetization took the maximum around M = Fe and Mn. This tendency was also seen in the cases of M being 4d transition metals, i.e., M = Ru and Mo. Our result indicates that magnetic moments at the pyramidal site have rather localized nature and largely affect the stability of the ferromagnetism of Y2M3Co9P7 although the ferromagnetism is considered to be mainly derived from three Co sites.
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14

FAROOQ, M. HASSAN, X. G. XU, H. L. YANG, C. J. RAN, Y. K. WANG, J. MIAO, and Y. JIANG. "INTRINSIC ROOM TEMPERATURE FERROMAGNETISM OF SILICON-DOPED ZnO THIN FILMS." Modern Physics Letters B 27, no. 13 (May 10, 2013): 1350092. http://dx.doi.org/10.1142/s0217984913500929.

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We report our study on the magnetic properties of Si -doped ZnO thin films fabricated by pulsed laser deposition technique. The Si -doped ZnO thin films show ferromagnetism at room temperature. The saturation magnetism increases from 0 to 2.4 emu/cc with the increasing of Si concentration up to 2%, and then decreases with further increasing of Si concentration. First-principles calculation demonstrates that the origination of ferromagnetism for Si -doped ZnO system is the two unpaired electrons of Si -2p. These unpaired electrons increase the magnetic moments which are responsible for the increasing ferromagnetism.
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15

Pachmayr, U., and D. Johrendt. "[(Li0.8Fe0.2)OH]FeS and the ferromagnetic superconductors [(Li0.8Fe0.2)OH]Fe(S1−xSex) (0 < x ≤ 1)." Chemical Communications 51, no. 22 (2015): 4689–92. http://dx.doi.org/10.1039/c5cc00038f.

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Superconductivity and ferromagnetism coexist in the iron chalcogenides [(Li0.8Fe0.2)OH]Fe(S1−xSex) until substitution of sulphur for selenium suppresses superconductivity while ferromagnetism persists.
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16

Mahmood, Qasim, Jameelah Alzahrani, and T. Ghrib. "Theoretical Investigation of Ferromagnetism and Optical Properties of CuCr2X4 (X = S, Se) Spinels via Ab-initio Calculations." Journal of Materials and Physical Sciences 3, no. 1 (June 30, 2022): 22–28. http://dx.doi.org/10.52131/jmps.2022.0301.0023.

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The spintronics technology improve the spin functionality which captivated the existence of ferromagnetism. The control of magnetic properties by electrons spin and transport effect have been illustrated in CuCr2X4 (X = S, Se) spinels DFT through Wien2k and BoltztraP codes. The negative formation of energy established the thermodynamic stability of the examined spinels. The half metallic ferromagnetism in the analyzed spinel’s assures density of states. Magnetic moment (Integer value) and the insulating nature with down spin is the reaction of 100% spin polarization. The negative attainment of the condition have presented the prevailing part of electrons spin to create ferromagnetism.
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17

Lipowski, Adam. "Ising Model: Recent Developments and Exotic Applications." Entropy 24, no. 12 (December 15, 2022): 1834. http://dx.doi.org/10.3390/e24121834.

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Solving in his PhD thesis the one-dimensional version of a certain lattice model of ferromagnetism formulated by his supervisor Lenz [1], Ising came to the conclusion that the model fails to describe finite-temperature ferromagnetism and does not seem to be particularly important [2]. [...]
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18

Wang, Yiren, Jingyuan Piao, Guozhong Xing, Yunhao Lu, Zhimin Ao, Nina Bao, Jun Ding, Sean Li, and Jiabao Yi. "Zn vacancy induced ferromagnetism in K doped ZnO." Journal of Materials Chemistry C 3, no. 45 (2015): 11953–58. http://dx.doi.org/10.1039/c5tc02936h.

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K doped ZnO shows room temperature ferromagnetism from both theoretical and experimental studies. This ferromagnetism is mainly attributed to the formation of the Zn vacancy. The K dopants can stabilize the Zn vacancy by forming a defect complex and K substitution can induce magnetism via lattice distortion.
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19

Concepción, Omar, Liesbeth Mulder, Daan H. Wielens, and Alexander Brinkman. "Thickness-Dependent Sign Change of the Magnetoresistance in VTe2 Thin Films." Solids 3, no. 3 (September 2, 2022): 500–507. http://dx.doi.org/10.3390/solids3030033.

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Transition metal dichalcogenides of type VX2 (X = S, Se, Te) have recently attracted great interest as it has been predicted that they host ferromagnetism at room temperature. Whether ferromagnetism is indeed present is an open experimental question. An in-depth study of the structural and magnetoelectric properties of VTe2 thin films is presented in this work. The VTe2 thin films were grown through molecular beam epitaxy, which allows for precise control of thicknesses, ranging from several nanometers down to monolayers. The low-temperature magnetoelectric transport studies reveal no sign of intrinsic ferromagnetism. However, a transition from positive to negative magnetoresistance is present upon decreasing film thickness.
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20

Xu, Gong Qin, Xiao Wei Chen, and Xing Yu Mao. "Possible Ferromagnetism in YCuO System." Solid State Phenomena 298 (October 2019): 181–85. http://dx.doi.org/10.4028/www.scientific.net/ssp.298.181.

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polycrystalline CuxYyOz are made through solid state reaction. Ferromagnetism is found in this YCuO system at room temperature. The ferromagnetism quite probably originates from Cu2Y2O5 , the Copper Yttrium Oxide. The average magnetic moment per Cu2+ is estimated to be 0.04μB. Itinerant electron magnetism is a rational explaination for the observed ferromagnetism. The experiment shows that the excessive amount of Cu may lead more defects and further distortion in the lattice and decrease the exchange interaction. This reminds us that the Copper Yttrium Oxide is a substance not only should be avoided in fabricating YBCO superconductors but also should be considered as a potential substance of magnetic semiconductor.
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21

Ren, Hongtao, Gang Xiang, Gangxu Gu, Xi Zhang, Wenjun Wang, Peng Zhang, Baoyi Wang, and Xingzhong Cao. "Zinc Vacancy-Induced Room-Temperature Ferromagnetism in Undoped ZnO Thin Films." Journal of Nanomaterials 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/295358.

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Undoped ZnO thin films are prepared by polymer-assisted deposition (PAD) and treated by postannealing at different temperatures in oxygen or forming gases (95% Ar+5% H2). All the samples exhibit ferromagnetism at room temperature (RT). SQUID and positron annihilation measurements show that post-annealing treatments greatly enhance the magnetizations in undoped ZnO samples, and there is a positive correlation between the magnetization and zinc vacancies in the ZnO thin films. XPS measurements indicate that annealing also induces oxygen vacancies that have no direct relationship with ferromagnetism. Further analysis of the results suggests that the ferromagnetism in undoped ZnO is induced by Zn vacancies.
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22

Baqiya, Malik Anjelh, Putu Eka Dharma Putra, Resky Irfanita, Suasmoro, Darminto, Takayuki Kawamata, Takashi Noji, Hidetaka Sato, Masatsune Kato, and Yoji Koike. "Enhanced Room-Temperature Ferromagnetism in Superconducting Pr2-xCexCuO4 Nanoparticles." Materials Science Forum 966 (August 2019): 263–68. http://dx.doi.org/10.4028/www.scientific.net/msf.966.263.

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Recently, the so-called room-temperature ferromagnetism in any nanoparticles has been studied intensively. It is well known that the properties of ferromagnetism and superconductivity are contradictory in a superconducting high-Tc cuprate. The existence of ferromagnetism in the nanoparticles has been suggested to occur on the surface. This magnetism has been expected to come from defects inducing magnetic moments on oxygen vacancies at the surface of the nanoparticles. This work is to observe magnetism in nanosized superconducting Pr2-xCexCuO4 (PCCO) with x = 0.15 by means of a superconducting quantum interference device (SQUID). The magnetization curves of the reduced PCCO nanoparticles with the superconducting transition temperature, Tc, of ~25 K have revealed that there is weak ferromagnetism observed at room temperature. The magnitude of magnetization could be enhanced by oxygen reduction annealing in vacuum with increasing annealing temperature. A non-linear magnetization occurring in the reduced PCCO nanoparticles through the vacuum annealing process is probably due to a strong oxygen reduction producing more oxygen vacancies in the T'-structure.
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23

Xing, Peng Fei, Shao Hua Sun, and Ping Wu. "Effect of Growth Atmosphere on the Structural, Optical and Magnetic Properties of Fe-Doped In2O3 Films." Advanced Materials Research 668 (March 2013): 757–61. http://dx.doi.org/10.4028/www.scientific.net/amr.668.757.

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Room temperature ferromagnetism was observed in Fe-doped In2O3 films deposited on fused quartz substrates by radiofrequency magnetron sputtering in N2 and O2 atmosphere, respectively. Results show that with increasing the O2 and N2 flux, the lattice constant increases, the optical band gap decreases, and the ferromagnetism weakens. Moreover, the decrease in the saturation magnetization for films deposited in N2 atmosphere is more apparent than that deposited in O2 atmosphere. We think the reason is that in our Fe-doped In2O3 films the ferromagnetism is mainly mediated by the oxygen vacancies, and as an acceptor defect, N ions can decrease the concentration of the oxygen vacancies to a greater extent than the O ions.
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24

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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25

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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26

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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27

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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28

Shavkatovich, Fayziev Shakhobiddin, Yuldasheva Nilufar Bakhtiyorovna, and Saidjonova Madinabonu Shuhratovna. "Weak ferromagnetism." ACADEMICIA: An International Multidisciplinary Research Journal 12, no. 1 (2022): 343–47. http://dx.doi.org/10.5958/2249-7137.2022.00054.4.

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29

Picozzi, Silvia. "Engineering ferromagnetism." Nature Materials 3, no. 6 (June 2004): 349–50. http://dx.doi.org/10.1038/nmat1137.

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30

ZHAO, JIAN-GUO, WEI-YING ZHANG, ER-QING XIE, XIU-YUN AN, JIE-CAI FU, ZHAO-JUN LIU, ZHONG-LI LIU, YA-JUAN ZHANG, YONG-FENG CHEN, and CHANG-YOU ZHANG. "ROOM-TEMPERATURE FERROMAGNETISM IN SnO2 NANOFIBERS AND NANOTUBES PREPARED BY ELECTROSPINNING." Nano 09, no. 02 (February 2014): 1450026. http://dx.doi.org/10.1142/s179329201450026x.

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SnO 2 nanofibers and nanotubes were synthesized by electrospinning method. Magnetization measurement indicates that the SnO 2 nanofibers and nanotubes annealed in air at 500°C exhibit the room-temperature ferromagnetism and the ferromagnetism of nanotubes is stronger than the nanofibers. Selected area electron diffraction, X-ray diffraction and Raman measurements show that all the samples possess a typical rutile structure and no other impurity phases are observed. The results of the Raman spectra also indicate that there are lots of defects existing in the fabricated samples. The observed room-temperature ferromagnetism in SnO 2 nanofibers and nanotubes possibly originates from oxygen vacancies. The field cooled (FC) and zero-field-cooled (ZFC) magnetization curves indicate that the Curie temperature TC is above 300 K.
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31

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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32

ERIKSSON, OLLE, R. C. ALBERS, A. M. BORING, G. W. FERNANDO, and B. R. COOPER. "ON THE PREDICTION OF FERROMAGNETISM AND METAMAGNETISM IN 4d TRANSITION-METAL OVERLAYERS." Modern Physics Letters B 06, no. 11 (May 10, 1992): 605–15. http://dx.doi.org/10.1142/s0217984992000703.

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We present theoretical evidence for ferromagnetism in Ru and Rh overlayers on Ag(001). These predictions are based on ab-initio, spin-polarized, electronic-structure calculations within the framework of the local spin-density approximation. For Tc, Ru, Rh and Pd overlayers chemisorbed on Ag(001), only Ru and Rh exhibited ferromagnetism. Several metamagnetic spin states were found for the Ru overlayers.
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33

Yun, Jiangni, Rui Qu, Zhiyong Zhang, and Jun Li. "Magnetic Properties of Well-Aligned ZnO Nanorod Arrays Grown by a Simple Hydrothermal Reaction." Advances in Condensed Matter Physics 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/627975.

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Well-aligned ZnO nanorod arrays with room temperature ferromagnetism were prepared on glass substrate through hydrothermal method. The as-prepared nanorod arrays were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), photoluminescence (PL) spectrum, and magnetization measurements. The XRD and SEM results indicated that the ZnO nanorods are with the wurtzite structure and exhibit preferential (002) orientation withc-axis perpendicular to the substrate surface. The PL results suggested that the possible defect in the as-prepared ZnO nanorod arrays might beVZn,Oi, orOZn. The first-principles calculations reveal that the room temperature ferromagnetism may result from theVZndefects present in the ZnO nanorod and the hybridization of the Zn 3d states with O 2p states is responsible for the half-metallic ferromagnetism in ZnO nanorod.
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34

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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35

KANEMATSU, KAZUO. "POSSIBILITY OF THERMALLY INDUCED FERROMAGNETISM IN YCo2.9Hy AND THE RELATED HYDRIDES." International Journal of Modern Physics B 07, no. 01n03 (January 1993): 903–6. http://dx.doi.org/10.1142/s0217979293001943.

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An anomalous, sharp peak in the susceptibi1ity near 200 K is observed in PuNi3 type hydrides Y1−xZrxCo2.9Hy (x<0.2, y=3−4). The peak reduces with time and then disappears. The absorbed hydrogen acts to make the cobalt magnetic moment decrease. According to Misawa theory based on Fermi- liquid description, susceptibi1ity maximum, thermally induced ferromagnetism and ferromagnetism occur with increase of a parameter, interaction strength. The inhomogeneous hydrogen distribution in the crystal may form locally areas of various interaction strength, also appropriate for thermally induced ferromagnetism, which is considered to be an origin of the susceptibility peak. The magnetic studies of Y(FexCo1−x)2.9Hy (y=3−4) were performed and the varation from the Pauli paramagnetism of anomalous peak to the ferommagnetism with increasing Fe concentration were interpreted by Misawa theory.
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36

Coey, J. M. D., and S. A. Chambers. "Oxide Dilute Magnetic Semiconductors—Fact or Fiction?" MRS Bulletin 33, no. 11 (November 2008): 1053–58. http://dx.doi.org/10.1557/mrs2008.225.

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AbstractMagnetism in oxides was thought to be well-understood in terms of localized magnetic moments and double-exchange or superexchange rules. This understanding was shaken by the publication of an article in 2001 stating that thin films of anatase TiO2 with only 7 at.% Co substitution had a Curie point in excess of 400 K [Matsumoto et al., Science291, 854 (2001)]. Room-temperature ferromagnetism had previously been predicted for p-type ZnO with 5 at.% Mn [Dietl et al., Science287, 1019 (2000)]. A flood of reports of thin films and nanoparticles of new oxide “dilute magnetic semiconductors” (DMSs) followed, and high-temperature ferromagnetism has been reported for other systems with no 3dcations. The expectation that these materials would find applications in spintronics motivated research in this area. Unfortunately, the data are plagued by instability and a lack of reproducibility. In many cases, the ferromagnetism can be explained by uncontrolled secondary phases; it is absent in well-crystallized films and bulk material. However, it appears that some form of high-temperature ferromagnetism can result from defects present in the oxide films [Coey, Curr. Opin. Solid State Mater. Sci.10, 83 (2007); Chambers, Surf. Sci. Rep.61, 345 (2006)], although they are not DMSs as originally envisaged.
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37

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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38

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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39

Jiao, Jun Rong, Jia Heng Wang, Chang Wei Gong, Yue Sheng Chai, and Wei Shao. "Structural, Optical and Magnetic Properties of W-Doped TiO2." Applied Mechanics and Materials 556-562 (May 2014): 330–34. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.330.

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Based on the density functional theory method, the ab initio calculation with GGA+U was performed to investigate the electronic structure and properties of W-doped TiO2. The results indicated that W-doping induced ferromagnetism and shifted the absorption spectra to visible light region. The ferromagnetism derived from the spin-split of O 2p and W 5d caused by p–d orbit hybridization. Several impurity bands under the conduction band decreased the band gap.
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40

Yokota, Takeshi, Yasutoshi Tsuboi, Shinya Kito, Rempei Imura, and Manabu Gomi. "Relationship between the Crystallinity and Magnetic Properties of Cr2O3/LiNbO3/Cr2O3 Multi-Layer Materials." Key Engineering Materials 485 (July 2011): 233–36. http://dx.doi.org/10.4028/www.scientific.net/kem.485.233.

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The magnetic properties of an artificial multiferroic material, a Cr2O3/LiNbO3/Cr2O3 hetero structure with various-thickness LiNbO3 layers, were investigated. All samples showed ferromagnetism due to the existence of oxygen deficiency or an excess of the Cr2O3 layer in the LNO/Cr2O3 interface. The ferromagnetism of the samples was affected by the crystal orientation of the LiNbO3 layer, and seemed to have a major impact on the magneto-electric behavior of this hetero system.
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41

Wang, Shiwei, Min Zhong, Cong Liu, Ying Li, Mingyuan Zhu, Hongming Jin, and Yemin Hu. "Effects of Temperature on the Microstructure and Magnetic Property of Cr-Doped ZnO DMS Prepared by Hydrothermal Route Assisted by Pulsed Magnetic Fields." Journal of Chemistry 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/830372.

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In the present work, Cr-doped ZnO diluted magnetic semiconductor was synthesized by hydrothermal method under pulsed magnetic fields. The samples were characterized by XRD, SEM, VSM, Raman, and XPS techniques. Results demonstrated that Zn ions in the ZnO crystal lattice were partially displaced by Chromium (III) ions. All samples show room temperature ferromagnetism which was enhanced by pulsed magnetic fields. The mechanism of ferromagnetism of Cr-doped ZnO particles was discussed.
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42

Thi Tran, Thanh-Mai, Duong-Bo Nguyen, Hong-Son Nguyen, and Minh-Tien Tran. "Magnetic competition in topological kagome magnets." Materials Research Express 8, no. 12 (December 1, 2021): 126101. http://dx.doi.org/10.1088/2053-1591/ac433c.

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Abstract Magnetic competition in topological kagome magnets is studied by incorporating the spin–orbit coupling, anisotropic Hund coupling and spin exchange into a tight-binding electron dynamics in the kagome lattice. Using the Bogoliubov variational principle we find the stable phases at zero and finite temperatures. At zero temperature and in the strong Ising-Hund coupling regime, a magnetic tunability from the out-of-plane ferromagnetism to the in-plane antiferromagnetism is achieved through a universal property of the critical in-plane Hund coupling. At low temperature the out-of-plane ferromagnetism is stable until a finite crossing temperature. Above the crossing temperature the in-plane antiferromagnetism is stable, but the magnetization of the out-of-plane ferromagnetism still survives. This suggests a metastable coexistence of these magnetic phases in a finite temperature range. A large anomalous Hall conductance is observed in the Ising-Hund coupling limit.
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43

Murata, Takeshi, Tomoyuki Terai, Takashi Fukuda, and Tomoyuki Kakeshita. "Magnetic Phase Diagram in Layered Perovskite Manganite La2-2xSr1+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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44

ELESIN, V. F., V. V. KAPAEV, and Yu V. KOPAEV. "MAGNETIC NESTING AND COEXISTENCE OF FERROMAGNETISM AND SUPERCONDUCTIVITY." International Journal of Modern Physics B 19, no. 01n03 (January 30, 2005): 189–91. http://dx.doi.org/10.1142/s0217979205028207.

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If the condition for magnetic nesting is fulfilled for the electron dispersion law with spin σ along a certain preferential direction n, ferromagnetism and the inhomogeneous superconducting state can coexist up to very high magnetization I. This fact was used to explain the coexistence of ferromagnetism and superconductivity for layered cuprates of the RuSr 2 GdCu 2 O 8 type, which possess a finite, though rather high critical magnetization, because the conditions for magnetic nesting are fulfilled only approximately.
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45

Guo, Chunsheng, Yu Zhou, Xin-Qiang Shi, Li-Yong Gan, Hong Jiang, and Yong Zhao. "Robust half-metallic ferromagnetism and curvature dependent magnetic coupling in fluorinated boron nitride nanotubes." Physical Chemistry Chemical Physics 18, no. 17 (2016): 12307–11. http://dx.doi.org/10.1039/c6cp01477a.

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46

Zhang, Xuanyi, Aubrey N. Penn, Lena Wysocki, Zhan Zhang, Paul H. M. van Loosdrecht, Lior Kornblum, James M. LeBeau, Ionela Lindfors-Vrejoiu, and Divine P. Kumah. "Thickness and temperature dependence of the atomic-scale structure of SrRuO3 thin films." APL Materials 10, no. 5 (May 1, 2022): 051107. http://dx.doi.org/10.1063/5.0087791.

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The temperature-dependent layer-resolved structure of 3 to 44 unit cell thick SrRuO3 (SRO) films grown on Nb-doped SrTiO3 substrates is investigated using a combination of high-resolution synchrotron x-ray diffraction and high-resolution electron microscopy to understand the role that structural distortions play in suppressing ferromagnetism in ultra-thin SRO films. The oxygen octahedral tilts and rotations and Sr displacements characteristic of the bulk orthorhombic phase are found to be strongly dependent on temperature, the film thickness, and the distance away from the film–substrate interface. For thicknesses, t, above the critical thickness for ferromagnetism ( t > 3 uc), the orthorhombic distortions decrease with increasing temperature above T C. Below T C, the structure of the films remains constant due to the magneto-structural coupling observed in bulk SRO. The orthorhombic distortions are found to be suppressed in the 2–3 interfacial layers due to structural coupling with the SrTiO3 substrate and correlate with the critical thickness for ferromagnetism in uncapped SRO films.
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47

Shu, Yu, Dongli Yu, Wentao Hu, Yanbin Wang, Guoyin Shen, Yoshio Kono, Bo Xu, Julong He, Zhongyuan Liu, and Yongjun Tian. "Deep melting reveals liquid structural memory and anomalous ferromagnetism in bismuth." Proceedings of the National Academy of Sciences 114, no. 13 (March 13, 2017): 3375–80. http://dx.doi.org/10.1073/pnas.1615874114.

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As an archetypal semimetal with complex and anisotropic Fermi surface and unusual electric properties (e.g., high electrical resistance, large magnetoresistance, and giant Hall effect), bismuth (Bi) has played a critical role in metal physics. In general, Bi displays diamagnetism with a high volumetric susceptibility (∼10−4). Here, we report unusual ferromagnetism in bulk Bi samples recovered from a molten state at pressures of 1.4–2.5 GPa and temperatures above ∼1,250 K. The ferromagnetism is associated with a surprising structural memory effect in the molten state. On heating, low-temperature Bi liquid (L) transforms to a more randomly disordered high-temperature liquid (L′) around 1,250 K. By cooling from above 1,250 K, certain structural characteristics of liquid L′ are preserved in L. Bi clusters with characteristics of the liquid L′ motifs are further preserved through solidification into the Bi-II phase across the pressure-independent melting curve, which may be responsible for the observed ferromagnetism.
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48

Ridene, Mohamed, Ameneh Najafi, and Kees Flipse. "Origin of Room-Temperature Ferromagnetism in Hydrogenated Epitaxial Graphene on Silicon Carbide." Nanomaterials 9, no. 2 (February 8, 2019): 228. http://dx.doi.org/10.3390/nano9020228.

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The discovery of room-temperature ferromagnetism of hydrogenated epitaxial graphene on silicon carbide challenges for a fundamental understanding of this long-range phenomenon. Carbon allotropes with their dispersive electron states at the Fermi level and a small spin-orbit coupling are not an obvious candidate for ferromagnetism. Here we show that the origin of ferromagnetism in hydrogenated epitaxial graphene with a relatively high Curie temperature (>300 K) lies in the formation of curved specific carbon site regions in the graphene layer, induced by the underlying Si-dangling bonds and by the hydrogen bonding. Hydrogen adsorption is therefore more favourable at only one sublattice site, resulting in a localized state at the Fermi energy that can be attributed to a pseudo-Landau level splitting. This n = 0 level forms a spin-polarized narrow band at the Fermi energy leading to a high Curie temperature and larger magnetic moment can be achieved due to the presence of Si dangling bonds underneath the hydrogenated graphene layer.
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49

Udagawa, Kota, Mariko Murayama, and Xinwei Zhao. "Ferromagnetism enhancement by increasing oxygen vacancies in Co-doped ZnO thin films." AIP Advances 12, no. 12 (December 1, 2022): 125221. http://dx.doi.org/10.1063/5.0099388.

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In the reported study, thin films of ZnO doped with 10 wt. % Co were fabricated by pulsed laser deposition under different oxygen partial pressures. The results of x-ray photoelectron spectroscopy show that the valence state of the Co ions is 2+ and that the number of oxygen vacancies is increased by lowering the oxygen partial pressure during deposition. The results of UV–visible absorption spectroscopy show that the Co2+ ions substitute for the Zn sites in the ZnO lattice. Ferromagnetism in the Co-doped ZnO thin films is observed up to 300 K. Furthermore, the saturation magnetization increases as the oxygen partial pressure decreases, indicating a strong correlation between the number of oxygen vacancies and the saturation magnetization. This suggests that ferromagnetism in Co-doped ZnO can be enhanced by simply controlling the oxygen partial pressure that causes oxygen vacancies. Furthermore, how the mechanism for the expression of ferromagnetism can be explained by the bound magnetic polaron model is discussed.
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50

Apostolov, Angel T., Iliana N. Apostolova, and Julia M. Wesselinowa. "A Theoretical Study of the Effects of Co-Doping Ions at K and Nb Sites on the Properties of KNbO3 Nanoparticles." Nanomaterials 14, no. 18 (September 10, 2024): 1473. http://dx.doi.org/10.3390/nano14181473.

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Using a microscopic model and Green’s function theory, we have investigated the co-doping effect on ferroelectric KNbO3 nanoparticles. Let us emphasize that while the doping with transition metal ions at the Nb site leads an increase in the ferromagnetism and a reduction the band gap, it also decreases the ferroelectricity. On the other hand, doping with La or Ba at the K site leads to enhanced polarization, but does not lead to the appearance of ferromagnetism and reduction in the band gap. Therefore, we have studied co-doping with La/Cr and La/Co ions, which leads to increasing the magnetization and polarization as well as to strongly decreasing the band gap energy. Thus, we observe a multiferroic material with room-temperature ferromagnetism and ferroelectricity as well as small band gap energy which can be tuned using various co-doping ions. There is a good agreement with the existing experimental data.
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