Artykuły w czasopismach: „Anomalous Hall coefficient”

1

Kaburagi, Y., i Y. Hishiyama. "Anomalous Hall coefficient in kish graphite". Carbon 33, nr 9 (1995): 1349–50. http://dx.doi.org/10.1016/0008-6223(95)93956-m.

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Yamada, K., H. Kontani, H. Kohno i S. Inagaki. "Anomalous Hall Coefficient in Heavy Electron Systems". Progress of Theoretical Physics 89, nr 6 (1.06.1993): 1155–66. http://dx.doi.org/10.1143/ptp/89.6.1155.

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Ōnuki, Y., T. Yamazaki, T. Omi, I. Ukon, A. Kobori, T. Komatsubara, A. Umezawa, W. K. Kwok, G. W. Crabtree i D. G. Hinks. "ANOMALOUS HALL COEFFICIENT IN Ce AND U COMPOUNDS". Le Journal de Physique Colloques 49, nr C8 (grudzień 1988): C8–797—C8–798. http://dx.doi.org/10.1051/jphyscol:19888361.

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Ōnuki, Yoshichika, Takashi Yamazaki, Isamu Ukon, Takemi Komatsubara, Ado Umezawa, Wai K. Kwok, George W. Crabtree i David G. Hinks. "Anomalous Hall Coefficient in thefElectron System– U Compounds". Journal of the Physical Society of Japan 58, nr 6 (15.06.1989): 2119–25. http://dx.doi.org/10.1143/jpsj.58.2119.

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Ōnuki, Yoshichika, Takashi Yamazaki, Takehiko Omi, Isamu Ukon, Atsuhisa Kobori i Takemi Komatsubara. "Anomalous Hall Coefficient in thefElectron system– Ce Compounds". Journal of the Physical Society of Japan 58, nr 6 (15.06.1989): 2126–34. http://dx.doi.org/10.1143/jpsj.58.2126.

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He, Zhenhui, Jiansheng Xia, Han Zhang, Minghu Fang, Shunxi Wang, Yitai Qian, Zuyao Chen i Qirui Zhang. "Anomalous Hall coefficient in ceramic materials YBa2Cu3?xSnxO7+?" Zeitschrift f�r Physik B Condensed Matter 78, nr 2 (czerwiec 1990): 191–94. http://dx.doi.org/10.1007/bf01307834.

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CHANG, P. H., H. C. YANG i H. E. HORNG. "ANOMALOUS HALL EFFECT NEAR Tc IN HIGH-Tc SUPERCONDUCTORS". Modern Physics Letters B 14, nr 15 (30.06.2000): 547–51. http://dx.doi.org/10.1142/s0217984900000719.

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A possible mechanism in the anomalous Hall coefficient in mixed state of high-T c superconductors was presented in this paper. The Hall voltage due to flux creep is the origin of the observed Hall anomaly. The calculated Hall coefficient exhibits a sign change as well as a re-entry behavior, which agree with experiments, qualitatively.

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Tousson, E., i Z. Ovadyahu. "Anomalous field dependence of the Hall coefficient in disordered metals". Physical Review B 38, nr 17 (15.12.1988): 12290–97. http://dx.doi.org/10.1103/physrevb.38.12290.

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ZHU, HUANGJUN. "ANOMALOUS HALL EFFECT IN PARAMAGNETIC 2DEG WITH LINEAR AND CUBIC DRESSELHAUS SPIN–ORBIT COUPLING". International Journal of Modern Physics B 24, nr 14 (10.06.2010): 2107–12. http://dx.doi.org/10.1142/s0217979210049800.

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We study the anomalous Hall effect in paramagnetic two-dimensional electron gas (2DEG) with both linear and cubic Dresselhaus spin–orbit coupling by means of Berry connection and Berry curvature. The effect of tuning the Fermi level and of tuning the cubic coupling coefficient on the anomalous Hall conductivity have been investigated semiclassically. Our results show that a sign reversal in the anomalous Hall conductivity may appear if the cubic Dresselhaus coefficient is very large and the Fermi surface is high enough, so the cubic Dresselhaus spin–orbit coupling term cannot be neglected in this case.

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10

Nishikawa, Takashi, Jun Takeda i Masatoshi Sato. "Anomalous Temperature Dependence of the Hall Coefficient inLa2-xSrxCuO4above Room Temperature". Journal of the Physical Society of Japan 62, nr 8 (15.08.1993): 2568–70. http://dx.doi.org/10.1143/jpsj.62.2568.

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Watanabe, Hiroshi, i Masao Ogata. "Anomalous changes of Fermi surface and Hall coefficient at quantum critical point". Physica B: Condensed Matter 403, nr 5-9 (kwiecień 2008): 1390–92. http://dx.doi.org/10.1016/j.physb.2007.10.141.

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Levin, George A., i Khandker F. Quader. "Quasi-two-dimensional Fermi system: Anomalous Hall coefficient and in-plane resistivity". Physical Review B 46, nr 9 (1.09.1992): 5872–75. http://dx.doi.org/10.1103/physrevb.46.5872.

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Fujiwara, Kohei, Yosuke Satake, Junichi Shiogai i Atsushi Tsukazaki. "Doping-induced enhancement of anomalous Hall coefficient in Fe-Sn nanocrystalline films for highly sensitive Hall sensors". APL Materials 7, nr 11 (1.11.2019): 111103. http://dx.doi.org/10.1063/1.5126499.

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Martini, Mickey, Helena Reichlova, Yejin Lee, Dominika Dusíková, Jan Zemen, Kornelius Nielsch i Andy Thomas. "Magneto-thermal transport indicating enhanced Nernst response in FeCo/IrMn exchange coupled stacks". Applied Physics Letters 121, nr 21 (21.11.2022): 212405. http://dx.doi.org/10.1063/5.0113485.

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We present an analysis of magneto-thermal transport data in IrMn/FeCo bilayers based on the Mott relation and report an enhancement of the Nernst response in the vicinity of the blocking temperature. We measure all four transport coefficients of the longitudinal resistivity, anomalous Hall resistivity, Seebeck effect, and anomalous Nernst effect, and we show a deviation arising around the blocking temperature between the measured Nernst coefficient and the one calculated using the Mott rule. We attribute this discrepancy to spin fluctuations at the antiferromagnet/ferromagnet interface near the blocking temperature. The latter is estimated by magnetometry and magneto-transport measurements.

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Takeda, Jun, Takashi Nishikawa i Masatoshi Sato. "Anomalous Behavior of Hall Coefficient and Thermoelectric Power ofYBa2Cu3O6+xandLa2-xSrxCuO4above Room Temperature". Journal of the Physical Society of Japan 62, nr 8 (15.08.1993): 2571–74. http://dx.doi.org/10.1143/jpsj.62.2571.

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Zhang, Peng, Weiwei Lin, Di Wu, Zhengsheng Jiang i Hai Sang. "Effective anomalous Hall coefficient in an ultrathin Co layer sandwiched by Pt layers". Journal of Applied Physics 115, nr 6 (14.02.2014): 063908. http://dx.doi.org/10.1063/1.4865791.

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Stephen, Jibu, Grant V. M. Williams i Benjamin J. Ruck. "Magnetotransport Study of Electron Doping in Sr₂FeMoO₆". Materials Science Forum 700 (wrzesień 2011): 19–22. http://dx.doi.org/10.4028/www.scientific.net/msf.700.19.

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We report the results from magnetotransport measurements on polycrystalline Sr2-xLaxFeMoO6 samples at magnetic fields of up to 8 T. We observe a normal as well as an anomalous Hall effect. We find that there is a small decrease in the normal Hall coefficient for La doped samples.

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Kuvadikov, O. K., N. C. Hamraev, R. M. Rajabov, A. A. Eshkulov i I. Turdibekov. "Relationship of kinetic and magnetic properties of intermetallic compounds of the Gd-In system in the paramagnetic region". Izvestiya vysshikh uchebnykh zavedenii. Fizika, nr 1 (2022): 3–8. http://dx.doi.org/10.17223/00213411/65/1/3.

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In this work experimental results on the electrical resistivity ρ, magnetic susceptibility c , and the Hall coefficient RH of intermetallic compounds of the Gd-In system in a wide temperature range are presented. On base of results of experimental studies, the normal R0 and anomalous RS components of the Hall coefficient were determined, and the zone parameters kF and EF were calculated, and the effective parameter of the spin-orbit interaction lS0 of the studied intermetallic compounds was estimated.

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Yu, Litao, Zhe Li, Jiajun Zhu, Hongwei Liu, Yuanlei Zhang, Yiming Cao, Kun Xu i Yongsheng Liu. "Electrical and Magnetic Transport Properties of Co2VGa Half-Metallic Heusler Alloy". Materials 15, nr 17 (4.09.2022): 6138. http://dx.doi.org/10.3390/ma15176138.

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This study performed a systematic experimental investigation into the structural, magnetic, and transport properties of the Co2VGa Heusler alloy, which was theoretically predicted to exhibit half-metallic ferromagnetism. It has been experimentally found that the studied alloy has a relatively high-ordered L21 cubic structure at room temperature and orders ferromagnetically below ~350 K. Interestingly, by fitting the electric transport data with the properly governing equations in two different temperature regions, the two-magnon scattering process (the T9/2 dependence) appears in the temperature range from 30 to 75 K. Moreover, the magnetoresistance effect changes from a negative value to a positive value when the temperature is below 100 K. Such experimental findings provide indirect evidence that the half-metallic nature of this alloy is retained only when the temperature is below 100 K. On the other hand, the magnetic transport measurements indicate that the anomalous Hall coefficient of this alloy increases when the temperature increases and reaches a relatively high value (~8.3 μΩ·cm/T) at 300 K due to its lower saturated magnetization. By analyzing the anomalous Hall resistivity scale with the longitudinal resistivity, it was also found that the anomalous Hall effect can be ascribed to the combined effect of extrinsic skew scattering and intrinsic Berry curvature, but the latter contribution plays a dominant role.

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Granovskii, A. B., A. V. Kalitsov i F. Brouers. "Field dependence of the anomalous Hall effect coefficient of granular alloys with giant Magnetoresistance". Journal of Experimental and Theoretical Physics Letters 65, nr 6 (marzec 1997): 509–13. http://dx.doi.org/10.1134/1.567384.

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Rafol, S. B., P. S. Wijewarnasuriya, S. Sivananthan i J. P. Faurie. "Hall electron density and mobility in HgCdTe alloys with anomalous behavior of the Hall coefficient in weak magnetic field". Journal of Applied Physics 74, nr 2 (15.07.1993): 1096–99. http://dx.doi.org/10.1063/1.354958.

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Demishev, S. V. "HOPPING TRANSPORT IN GALLIUM ANTIMONIDE". International Journal of Modern Physics B 08, nr 07 (30.03.1994): 865–73. http://dx.doi.org/10.1142/s0217979294000403.

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This report summarizes a study of hopping transport in doped crystalline and amorphous gallium antimonide. The experimental results demonstrate the importance of short-range correlations rather than Coulomb ones. Anomalous behaviour of the Hall coefficient and the thermoelectric power is described.

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ILONCA, G., A. V. POP, M. ILONCA, E. MACOCIAN, T. JURCUT, R. STIUFIUC i V. TOMA. "GALVANOMAGNETIC EFFECTS AND ELECTRONIC SPECIFIC HEAT OF BULK La2-xBaxCu1-yZnyO4+d". International Journal of Modern Physics B 16, nr 24 (20.09.2002): 3587–94. http://dx.doi.org/10.1142/s0217979202012177.

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The samples of bulk La 2-x Ba x Cu 1-y Zn y O 4+d were prepared by conventional solid state reaction method and have been investigated using electrical resistivity, Seebeck coefficient, Hall coefficient and electronic specific heat measurements over the temperature range between 4.2 K and 300 K in magnetic fields up to 5 T. The samples with y = 0 and d = 0 showed superconductivity for x between 0.055 and 0.30. The critical temperature, the Hall and Seebeck coefficients depend strongly on Zn contents. The phonon specific heat and electronic specific heat have been extracted from the total specific heat, where anomalous x, y and T dependence related to the so-called 1/8 anomaly or the "stripe order" is observed. Zn-doping effect or the behavior γ (T) = Cel/T suggest that large range stripe order and the fluctuating "stripe" suppress the singlet formation and pseudo-gap.

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Ito, Keita, Jian Wang, Yusuke Shimada, Himanshu Sharma, Masaki Mizuguchi i Koki Takanashi. "Enhancement of the anomalous Nernst effect in epitaxial Fe₄N films grown on SrTiO₃(001) substrates with oxygen deficient layers". Journal of Applied Physics 132, nr 13 (7.10.2022): 133904. http://dx.doi.org/10.1063/5.0102928.

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Anomalous Nernst effect of epitaxial Fe4N films on MgO(001), MgAl2O4(MAO)(001), and SrTiO3(STO)(001) substrates grown by molecular beam epitaxy was investigated. Moderately large anomalous Nernst coefficients ( SANE) of 1.4 and 1.7 μV/K were obtained in the Fe4N films on the MgO(001) and MAO(001) substrates, respectively, and large anomalous Hall angles (∼0.06) and transverse thermoelectric conductivities [∼1.3 A/(m K)] were derived from the experimental results. On the other hand, a large effective SANE of 2.8 μV/K was obtained in the Fe4N film on the STO(001) substrate. The origin of the enhanced effective SANE is the negatively large Seebeck coefficient ( SSE) in an oxygen deficient STO layer near the surface of the STO substrate. This indicates that it is possible to enhance the effective SANE of ferromagnetic materials by utilizing adjacent materials with large | SSE| such as the oxygen deficient STO layer.

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Gu, Haiyang, Jianjun Tian, Chaoyang Kang, Longsheng Wang, Rui Pang, Mengna Shen, Kai Liu i in. "Sign change of anomalous Hall effect with temperature in Cr_2.63V_0.25Te₄ single crystal". Applied Physics Letters 121, nr 19 (7.11.2022): 191906. http://dx.doi.org/10.1063/5.0108940.

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Anomalous Hall effect, an interesting transport behavior, is of importance topic for fundamental physics and device application. Recently, the sign change of anomalous Hall effect (AHE) in some materials has being concerned. Here, we study the electrical transport, magnetic properties, and AHE of Cr2.63V0.25Te4 single crystals. Cr2.63V0.25Te4 shows a bad metal behavior with a resistivity kink at 178 K, corresponding to a peak on a heat capacity–temperature curve, and the strong electron correlation should be a dominant transport mechanism below 178 K. At this temperature, the magnetization shows a sharp magnetic transition. The linear Hall resistivity at a high field with a positive slope suggests a p-type conductivity for bulk Cr2.63V0.25Te4. The clear AHE is observed below 180 K with a larger anomalous Hall conductivity σxy ∼ 2000 Ω−1 cm−1 at 3 K. For 3–60 K, an AHE coefficient Rs is negative, and Rs is positive between 100 and 180 K. The sign change of AHE may be due to Fermi level crossing the overlap of 3 d band in ferromagnetic transition-metal materials. Based on our analysis, the AHE mechanism should be the skew scattering. Our results reveal the interesting physical properties in Cr2.63V0.25Te4 single crystals and give another system to study AHE for future Hall device design.

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Choi, H. K., W. O. Lee, Y. S. Oh, K. H. Kim i Y. D. Park. "Non-monotonic dependence of the anomalous Hall coefficient scaling parameter in annealed Ga1−xMnxAs epifilms". Journal of Magnetism and Magnetic Materials 310, nr 2 (marzec 2007): 2129–31. http://dx.doi.org/10.1016/j.jmmm.2006.10.935.

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Yin, Weida, Keita Ito, Yusuke Tsubowa, Masahito Tsujikawa, Masafumi Shirai i Koki Takanashi. "Anomalous Nernst effect in epitaxially grown Fe_4−xNi_xN films". AIP Advances 13, nr 2 (1.02.2023): 025243. http://dx.doi.org/10.1063/9.0000564.

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Anomalous Nernst effect of epitaxial Fe4− xNi xN films on MgAl2O4(001) substrates was characterized. The Ni/Fe ratio ( x) in Fe4− xNi xN films was changed in the range of 0 ≤ x ≤ 2.8, and the Fe4− xNi xN phase started to decompose into FeNi at about x = 2.2. The anomalous Nernst coefficient ( SANE) decreased with x from 1.7 to 0.6 μV/K and the Seebeck coefficient increased with x from −2.3 to 1.2 μV/K. The transverse thermoelectric conductivity ( αxy) evaluated from the experimental data showed a decrease with x and the change of αxy dominated the change of SANE. The anomalous Hall conductivity and αxy of Fe4N and Fe2.8Ni1.2N were obtained by first-principles calculations, showing a significant difference from the experimental results, which might be caused by the contribution from the extrinsic mechanisms.

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Sun, Yiming, Liangwei Wu, Mengmeng Yang, Mengjia Xia, Wei Gao, Dongxiang Luo, Nengjie Huo i Jingbo Li. "Anomalous Hall Effect and Magneto-Optic Kerr Effect in Pt/Co/Pt Heterostructure". Magnetochemistry 8, nr 5 (12.05.2022): 56. http://dx.doi.org/10.3390/magnetochemistry8050056.

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Magnetic multilayer with large perpendicular magnetic anisotropy (PMA) has attracted sustained interest owing to its importance to fundamental physics and applications. In this work, the high quality of Pt/Co/Pt heterostructures with large PMA was successfully achieved to exhibit a large anomalous Hall effect (AHE) with squared Hall loops. By calculating the proportional relationship between the longitudinal resistivity (ρxx) and the abnormal Hall coefficient (Rs), it is confirmed that the basic mechanism of AHE comes from the external skew scattering (SS) and side jump (SJ), while SS contribution, related to asymmetric scattering from impurities, is dominant in the AHE. Furthermore, the obvious magneto-optical Kerr effect (MOKE) was also observed using the polar MOKE microscopy. The obviously circular magnetic domain can form and propagate in response to the applied out-of-plane magnetic field, resulting in the magnetization reversal of the entire film. This work offers important information in terms of both AHE and MOKE in the ultrathin ferromagnetic films with perpendicular anisotropy, establishing the application foundation for the nonvolatile memories and spintronics.

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Rathkanthiwar, Shashwat, Pegah Bagheri, Dolar Khachariya, Seiji Mita, Cristyan Quiñones-García, Yan Guan, Baxter Moody i in. "High conductivity and low activation energy in p-type AlGaN". Applied Physics Letters 122, nr 9 (27.02.2023): 092103. http://dx.doi.org/10.1063/5.0141863.

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Record-low p-type resistivities of 9.7 and 37 Ω cm were achieved in Al0.7Ga0.3N and Al0.8Ga0.2N films, respectively, grown on single-crystal AlN substrate by metalorganic chemical vapor deposition. A two-band conduction model was introduced to explain the anomalous thermal behavior of resistivity and the Hall coefficient. Relatively heavy Mg doping (5 × 1019 cm−3), in conjunction with compensation control, enabled the formation of an impurity band exhibiting a shallow activation energy of ∼30 meV for a wide temperature range. Valence band conduction associated with a large Mg ionization energy was dominant above 500 K. The apparently anomalous results deviating from the classical semiconductor physics were attributed to fundamentally different Hall scattering factors for impurity and valence band conduction. This work demonstrates the utility of impurity band conduction to achieve technologically relevant p-type conductivity in Al-rich AlGaN.

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Arjona, Vicente, Juan Borge i María A. H. Vozmediano. "Thermoelectric Relations in the Conformal Limit in Dirac and Weyl Semimetals". Symmetry 12, nr 5 (14.05.2020): 814. http://dx.doi.org/10.3390/sym12050814.

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Dirac and Weyl semimetals are three-dimensional electronic systems with the Fermi level at or near a band crossing. Their low energy quasi-particles are described by a relativistic Dirac Hamiltonian with zero effective mass, challenging the standard Fermi liquid (FL) description of metals. In FL systems, electrical and thermo–electric transport coefficient are linked by very robust relations. The Mott relation links the thermoelectric and conductivity transport coefficients. In a previous publication, the thermoelectric coefficient was found to have an anomalous behavior originating in the quantum breakdown of the conformal anomaly by electromagnetic interactions. We analyze the fate of the Mott relation in the system. We compute the Hall conductivity of a Dirac metal as a function of the temperature and chemical potential and show that the Mott relation is not fulfilled in the conformal limit.

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Choi, H. K., Y. S. Kim, S. S. A. Seo, I. T. Jeong, W. O. Lee, Y. S. Oh, K. H. Kim i in. "Evidence of metallic clustering in annealed Ga1−xMnxAs from atypical scaling behavior of the anomalous Hall coefficient". Applied Physics Letters 89, nr 10 (4.09.2006): 102503. http://dx.doi.org/10.1063/1.2344932.

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Katayama, Kazuhiro, Takuya Nagai, Hiromi Taniguchi, Kazuhiko Satoh, Naoya Tajima i Reizo Kato. "Anomalous sign change in hall coefficient of κ-(BEDT-TTF)2Cu[N(CN)2]Br under pressure". Journal of Low Temperature Physics 142, nr 3-4 (luty 2006): 515–18. http://dx.doi.org/10.1007/bf02679558.

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Katayama, Kazuhiro, Takuya Nagai, Hiromi Taniguchi, Kazuhiko Satoh, Naoya Tajima i Reizo Kato. "Anomalous Sign Change in Hall Coefficient of κ-(BEDT-TTF)2Cu[N(CN)2]Br Under Pressure". Journal of Low Temperature Physics 142, nr 3-4 (20.01.2007): 519–22. http://dx.doi.org/10.1007/s10909-006-9155-2.

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Ausloos, M., i S. Dorbolo. "Cooper Pair-Like Systems at High Temperature and their Role on Fluctuations Near the Critical Temperature". International Journal of Modern Physics B 12, nr 29n31 (20.12.1998): 3216–19. http://dx.doi.org/10.1142/s0217979298002349.

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A logarithmic behavior is hidden in the linear temperature regime of the electrical resistivity R(T) of some YBCO sample below 2T c where "pairs" break apart, fluctuations occur and "a gap is opening". An anomalous effect also occurs near 200 K in the normal state Hall coefficient. In a simulation of oxygen diffusion in planar 123 YBCO, an anomalous behavior is found in the oxygen-vacancy motion near such a temperature. We claim that the behavior of the specific heat above and near the critical temperature should be reexamined in order to show the influence and implications of fluctuations and dimensionality on the nature of the phase transition and on the true onset temperature.

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Matsuura, Hideharu, Rinya Nishihata, Akinobu Takeshita, Kohei Ogawa, Tatsuya Imamura, Kota Takano, Kazuya Okuda i in. "Anomalous Temperature Dependence of the Hall Coefficient of Heavily Al-Doped 4H-SiC Epilayers in the Band Conduction Region". Materials Science Forum 1004 (lipiec 2020): 215–23. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.215.

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We investigate the temperature dependence of the resistivity and Hall coefficient for heavily Al-doped p-type 4H-SiC epilayers with Al concentrations (C_Al) of > 2E19 cm^−3, which are substrates for the collectors of insulated-gate bipolar transistors. The signs of the measured Hall co- efficients (R_H) changed from positive to negative at low temperatures. For epilayers with C_Al values of < 3E19 cm^−3, a negative R_H was observed in the hopping conduction region. In contrast, for epilayers with C_Al values of > 3E19 cm^−3, a negative R_H was observed in not only the hopping conduction region but also the band conduction region, which is a striking feature because the movement of free holes in the valence band should make R_H positive. For an epilayer with C_Al of 1.8E20 cm^−3, the sign of R_H clearly changed three times in the band conduction region. Moreover, the activation energies of the temperature-dependent R_H values were similar to those of the temperature-dependent resistivity in the corresponding temperature ranges, irrespective of the conduction mechanisms (band and hopping conduction).

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Скипетров, Е. П., Б. Б. Ковалев, Л. А. Скипетрова, А. В. Кнотько i В. Е. Слынько. "Термический коэффициент движения резонансного уровня железа в сплавах Pb-=SUB=-1-x-y-=/SUB=-Sn-=SUB=-x-=/SUB=-Fe-=SUB=-y-=/SUB=-Te". Физика и техника полупроводников 53, nr 11 (2019): 1459. http://dx.doi.org/10.21883/ftp.2019.11.48440.9141.

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The phase composition, the elemental composition and temperature dependences of the resistivity and of the Hall coefficient (temperature interval 4.2≤T≤300K, magnetic fields B≤0.07 T) in Pb1−x−ySnxFeyTe alloys are studied at variation of the tin and iron concentrations along the single-crystal ingots synthesized by the Bridgman−Stockbarger technique. The distributions of tin and iron along the ingots are obtained and anomalous temperature dependences of the Hall coefficient, associated with the pinning of the Fermi level by the resonant level of iron, located in the valence band, are found. The analysis of the experimental results is carried out in the framework of the model of the electronic structure rearrangement, involving the movement of the iron level relative to the top of the valence band with increasing tin concentration and temperature. The temperature coefficient of the movement of the level of iron with respect to the middle of the gap is determined and the possible diagrams for the rearrangement of the electronic structure with increasing temperature in the alloys with normal spectrum (0.06≤x≤0.35) are proposed.

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Hong, Deshun, Changjiang Liu, Jianguo Wen, Qianheng Du, Brandon Fisher, J. S. Jiang, John E. Pearson i Anand Bhattacharya. "Synthesis of antiferromagnetic Weyl semimetal Mn₃Ge on insulating substrates by electron beam assisted molecular beam epitaxy". APL Materials 10, nr 10 (1.10.2022): 101113. http://dx.doi.org/10.1063/5.0116981.

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The antiferromagnetic kagome semimetals Mn3X (X = Ge, Sn, Ga) are of great interest due to properties arising from their Berry curvature, such as large anomalous Nernst and anomalous Hall coefficients, and spin to charge conversion efficiencies at ambient temperatures. However, the synthesis of epitaxial thin films of Mn3Ge in the desired hexagonal phase has been challenging because they do not wet insulating substrates, necessitating the use of a metallic buffer layer. Furthermore, a ferrimagnetic tetragonal phase also forms readily under typical growth conditions, interfering with hexagonal phase properties. We have synthesized atomically smooth and continuous epitaxial thin films of hexagonal Mn3Ge directly on insulating LaAlO3 (111) substrates using electron beam assisted molecular beam epitaxy, using a three-step process that mitigates the formation of the tetragonal phase. The anomalous Nernst coefficient is found to be more than six times larger in our films than in sputtered thin films of Mn3Ge and significantly larger than that of Fe. Our approach can be used to grow thin layers of kagome materials, without interference from a buffer layer in transport properties, and may be applicable to a broader range of materials with large surface energies that do not grow readily on insulating substrates.

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Rathkanthiwar, Shashwat, Pegah Bagheri, Dolar Khachariya, Ji Hyun Kim, Yasutomo Kajikawa, Pramod Reddy, Seiji Mita i in. "On the conduction mechanism in compositionally graded AlGaN". Applied Physics Letters 121, nr 7 (15.08.2022): 072106. http://dx.doi.org/10.1063/5.0100756.

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A two-band transport model is proposed to explain electrical conduction in graded aluminum gallium nitride layers, where the free hole conduction in the valence band is favored at high temperatures and hopping conduction in the impurity band dominates at low temperatures. The model simultaneously explains the significantly lowered activation energy for p-type conduction (∼10 meV), a nearly constant sheet conductivity at lower temperatures (200–330 K), and the anomalous reversal of the Hall coefficient caused by the negative sign of the Hall scattering factor in the hopping conduction process. A comparison between the uniform and graded samples suggests that compositional grading significantly enhances the probability of phonon-assisted hopping transitions between the Mg atoms.

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39

Marchenkov, Vyacheslav V., Sabina M. Emelyanova i Elena B. Marchenkova. "Martensitic Transformation Temperatures and Hall Effect in Ni47−xMn41+xIn12 (x = 0, 1, 2) Alloys". Materials 16, nr 2 (10.01.2023): 672. http://dx.doi.org/10.3390/ma16020672.

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At present, the question of the relationship between the characteristic martensitic transformation temperatures (MTT) and the electronic parameters of a system has not been fully studied. In the present work, an attempt to establish a similar relationship using the example of the concentration of charge carriers, n, was made. The field dependences of Hall resistivity ρH and magnetization M of the magnetocaloric Ni47−xMn41+xIn12 (x = 0, 1, 2) alloys were measured at T = 4.2 K and in magnetic fields of up to 80 kOe. The MTT were obtained from the temperature dependences of electrical resistivity and magnetization. It was observed that the MTT correlate strongly with both the valence electron concentration e/a and the electronic transport characteristics, which are the coefficient of the normal (NHE) R0 and anomalous (AHE) RS Hall effect and the concentration of charge carriers n.

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40

Elbistan, Mahmut. "Weyl semimetal and topological numbers". International Journal of Modern Physics B 31, nr 29 (7.11.2017): 1750221. http://dx.doi.org/10.1142/s0217979217502216.

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Generalized Dirac monopoles in momentum space are constructed in even [Formula: see text] dimensions from the Weyl Hamiltonian in terms of Green’s functions. In [Formula: see text] dimensions, the (unit) charge of the monopole is equal to both the winding number and the Chern number, expressed as the integral of the Berry curvature. Based on the equivalence of the Chern and winding numbers, a chirally coupled and Lorentz invariant field theory action is studied for the Weyl semimetal phase. At the one loop order, the effective action yields both the chiral magnetic effect and the anomalous Hall effect. The Chern number appears as a coefficient in the conductivity, thus emphasizes the role of topology. The anomalous contribution of chiral fermions to transport phenomena is reflected as the gauge anomaly with the Pfaffian invariant [Formula: see text]. Relevance of monopoles and Chern numbers for the semiclassical chiral kinetic theory is also discussed.

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41

Stepanov, N. P. "Revisiting the Nature of the Anomalous Temperature Dependence of the Hall Coefficient Observed for Semiconductor Crystals of Bi2Te3–Sb2Te3 Solid Solutions". Semiconductors 54, nr 1 (styczeń 2020): 11–14. http://dx.doi.org/10.1134/s1063782620010224.

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42

Скипетров, Е. П., Б. Б. Ковалев, И. В. Шевченко, А. В. Кнотько i В. Е. Слынько. "Влияние примеси никеля на гальваномагнитные свойства и электронную структуру PbTe". Физика и техника полупроводников 54, nr 10 (2020): 987. http://dx.doi.org/10.21883/ftp.2020.10.49932.9417.

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The phase and elemental composition and galvanomagnetic properties (4.2 < T < 300 K, B < 7 T) of Pb1-yNiyTe alloys are studied at a variation of the nickel impurity concentration along the single-crystal ingot synthesized by the Bridgman-Stockbarger technique. It is shown that the solubility of nickel does not exceed 0.35 mol %. Anomalous temperature dependences of the Hall coefficient and temperature and field dependences of magnetoresistance are found. To explain the results, it is assumed that an n-type inversion layer appears on the surface of the samples and that there are several competing conduction mechanisms in the samples. A model of the Pb1-yNiyTe electronic structure is proposed that assumes pinning of the Fermi level within the Ni impurity band, located at the edge of the valence band and moving deeper into it with increasing temperature.

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43

Rani, Deepika, Devendra K. Pandey, Yuta Kimura, Rie Y. Umetsu i Ratnamala Chatterjee. "Structural, magnetic, and transport properties of epitaxial thin films of equiatomic quaternary CoFeCrGa Heusler alloy". Journal of Applied Physics 132, nr 19 (21.11.2022): 193907. http://dx.doi.org/10.1063/5.0127548.

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We present the first report on the structural, magnetic, and transport properties of epitaxial thin films of equiatomic quaternary CoFeCrGa, grown on a single crystal MgO(001) substrate. From the structure and surface morphology analyses, we have shown that the films grown are ordered, epitaxial, and homogeneous. Magnetic measurements confirm the soft ferromagnetic nature of the film along the in-plane direction with a coercivity of 4.6 Oe. The resistivity measurements indicate semiconducting nature with a very low temperature coefficient of resistivity (TCR) value, suggesting an almost temperature independent resistivity, similar to other reported spin-gapless semiconductors (SGSs) among the Heusler alloys. A non-saturating, quantum linear magnetoresistance is observed even in high fields of up to 12 kOe, another prerequisite for gapless materials. Hall measurements are also performed, and a detailed analysis has been carried out to estimate the ordinary and anomalous Hall contributions. The conductivity value ([Formula: see text]) at 300 K is found to be 4280 S cm[Formula: see text], which is comparable with the other reported SGS materials. We have also studied the effect of L2[Formula: see text] and B2 type disorder on the electronic properties based on the first principle calculations and found that the SGS nature in CoFeCrGa is quite robust against the Co–Fe swap disorder (L2[Formula: see text] disorder); however, with swap disorder ([Formula: see text]%) between Cr and Ga sites, the system transits from SGS to half-metallic state. All these results indicate the possibility of spin-gapless semiconducting nature in the CoFeCrGa film, making it highly suitable for spin-based device applications.

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44

Fang, Yuankan, Sheng Ran, Weiwei Xie, Shen Wang, Ying Shirley Meng i M. Brian Maple. "Evidence for a conducting surface ground state in high-quality single crystalline FeSi". Proceedings of the National Academy of Sciences 115, nr 34 (6.08.2018): 8558–62. http://dx.doi.org/10.1073/pnas.1806910115.

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We report anomalous physical properties of high-quality single-crystalline FeSi over a wide temperature range of 1.8–400 K. The electrical resistivity ρ(T) can be described by activated behavior with an energy gap Δ = 57 meV between 150 and 67 K, below which the estimated energy gap is significantly smaller. The magneto-resistivity and Hall coefficient change sign in the vicinity of 67 K, suggesting a change of dominant charge carriers. At ∼19 K, ρ(T) undergoes a cross-over from semiconducting to metallic behavior which is very robust against external magnetic fields. The low-temperature metallic conductivity depends strongly on the width/thickness of the sample. In addition, no indication of a bulk-phase transition or onset of magnetic order is found down to 2 K from specific heat and magnetic susceptibility measurements. The measurements are consistent with one another and point to complex electronic transport behavior that apparently involves a conducting surface state in FeSi at low temperatures, suggesting the possibility that FeSi is a 3D topological insulator.

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45

Misawa, Setsuo. "The 3-Dimensional Fermi Liquid Description for the Iron-Based Superconductors". Journal of Low Temperature Physics 190, nr 1-2 (19.09.2017): 45–66. http://dx.doi.org/10.1007/s10909-017-1811-1.

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Abstract The quasiparticles in the normal state of iron-based superconductors have been shown to behave universally as a 3-dimensional Fermi liquid. Because of interactions and the presence of sharp Fermi surfaces, the quasiparticle energy contains, as a function of the momentum $$\varvec{p}$$ p , a term of the form $$( p - p_0)^3 \ln {( |p-p_0|/p_0)} $$ ( p - p 0 ) 3 ln ( | p - p 0 | / p 0 ) , where $$p = | \varvec{p} |$$ p = | p | and $$p_0$$ p 0 is the Fermi momentum. The electronic specific heat coefficient, magnetic susceptibility (Knight shift), electrical resistivity, Hall coefficient and thermoelectric power divided by temperature follow, as functions of temperature T, the logarithmic formula $$a-b T^2 \ln {(T/T^*)}$$ a - b T 2 ln ( T / T ∗ ) , $$a, \, b$$ a , b and $$T^*$$ T ∗ being constant; these formulae have been shown to explain the observed data for all iron-based superconductors. It is shown that the concept of non-Fermi liquids or anomalous metals which appears in the literature is not needed for descriptions of the present systems. When the superconducting transition temperature $$T_{\mathrm {C}}$$ T C and the b / a value for the resistivity are plotted as functions of the doping content x, there appear various characteristic diagrams in which regions of positive correlation and those of negative correlation between $$T_{\mathrm {C}}$$ T C and b / a are interconnected; from these diagrams, we may make speculations about the types of superconductivity and the crossover between them.

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46

Nava, F., P. A. Psaras, H. Takai, K. N. Tu, S. Valeri i O. Bisi. "Electrical and structural characterization of Nb-Si thin alloy film". Journal of Materials Research 1, nr 2 (kwiecień 1986): 327–36. http://dx.doi.org/10.1557/jmr.1986.0327.

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The structural and electrical properties of a Nb-Si thin alloy film as a function of temperature have been studied by Auger electron spectrometry, Rutherford backscattering spectroscopy, transmission electron microscopies, and in situ electrical resistivity and Hall coefficient measurements. The NbSi2,8 films were deposited by double electron-gun coevaporation onto oxidized silicon. For electrical measurements samples of a van der Pauw pattern were made through metallic masks. In the as-deposited state the coevaporated alloy film was amorphous. Upon annealing a precipitous drop in resistivity near 270°C has been determined to be the amorphous to crystalline phase transformation. The kinetics of the transformation has been determined by isothermal heat treatment over the temperature range of 224°C to 252°C. An apparent activation energy of 1.90 eV has been measured. The nucleation and growth kinetics in the crystallization process show a change in the power of time dependence from 5.5 to 2.4. The microstructures of films at various states of annealing have been correlated to the resistivity change. The crystalline NbSi2 shows an anomalous metallic behavior. The resistivity (p) versus temperature curve has a large negative deviation from linearity (dfl) and it approaches a saturation value (psat) as temperature increases. The resistivity data are fitted by two empirical expressions put forth to explain the resistivity behavior in A15 superconductors at low and high temperatures. One is based on the idea that ideal resistivity must approach some limiting value in the regime where the mean free path becomes comparable to the interatomic spacing and the other is based on a selective electron-phonon assisted scattering. In spite of the wide temperature range of analysis, it is not possible to choose one of them due to the fact that the best fit in both cases is nearly the same. The Hall coefficient (RH) changes sign from negative above ∼250°K to positive below ∼ 250°K.

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47

Ushio, Hideki, i Hiroshi Kamimura. "III. Energy Bands, Fermi Surfaces and Density of States of the Hole Carriers in the Presence of the Local Antiferromagnetic Ordering". International Journal of Modern Physics B 11, nr 32 (30.12.1997): 3759–96. http://dx.doi.org/10.1142/s0217979297001933.

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We have separated a hole carrier and a localized spin, by treating the exchange interaction between the spins of a carrier hole and a localized spin in a mean field sense. Then we have constructed the effective one-electron-type band structure for the hole carriers in the presence of the antiferromagnetic (AF) ordering of the localized spins. In the case of the undoped La2CuO4 all the energy bands are fully occupied by electrons so that La2CuO4 is an insulator. In this sense the present energy bands which include the many body effect fully is completely different from the ordinary energy band in the local density functional method. The top of the highest valence band is at (π/a, π/a, 0)-point, and the calculated Fermi surface is small as far as the spin correlation length of the AF order is larger than the mean free path. Based on this energy band and Fermi surfaces we have calculated various normal state properties and explained their anomalous features, such as the x-dependence of the electronic specific heat, the linear temperature dependence of the resistivity down to T c , the x-dependence of the Hall coefficient with the sign change, the large T dependence of R H , the incommensurate peak of the neutron scattering and the instability at x=0.125.

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48

Sluchanko, N. E., V. V. Glushkov, S. V. Demishev, M. V. Kondrin, K. M. Petukhov, A. A. Pronin, N. A. Samarin, Y. Bruynseraede, V. V. Moshchalkov i A. A. Menovsky. "Low-temperature anomalies of the Hall coefficient in FeSi". Journal of Experimental and Theoretical Physics Letters 68, nr 10 (listopad 1998): 817–22. http://dx.doi.org/10.1134/1.567951.

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Rosenbaum, Ralph, i Tim Murphy. "Anomalous Hall coefficients of a polycrystalline Bismuth film measured in parallel magnetic fields". Physica B: Condensed Matter 346-347 (kwiecień 2004): 296–300. http://dx.doi.org/10.1016/j.physb.2004.01.093.

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MACDONALD, A. H. "ANOMALOUS TRANSPORT IN METALS AND SEMICONDUCTORS". International Journal of Modern Physics B 22, nr 01n02 (20.01.2008): 120. http://dx.doi.org/10.1142/s0217979208046219.

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According to the Kubo formula, the static uniform electric fields in a metal or semiconductor can induce coherence between band states far from the Fermi energy. This interband coherence response appears to be at odds with the normal view that transport is a Fermi-energy property, and is relatively unfamiliar since it makes a negligibly small contribution to the most commonly studied transport coefficients such as the longitudinal conductivity. It has recently been argued that interband coherence response can dominate the anomalous Hall conductivity of ferromagnetic metals and semiconductors and the spin-Hall conductivity of paramagnetic materials. I will review recent theoretical ideas related to the charge Hall conductivity of ferromagnetic materials and the spin Hall conductivity of paramagnetic materials and their relation to recent and future experiments. Note from Publisher: This article contains the abstract only.

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