We have investigated the anisotropic magnetoresistance (AMR) of (In,Fe)As ferromagnetic semiconductor (FMS) layers grown on semi-insulating GaAs substrates. In a 10 nm-thick (In,Fe)As layer which is insulating at low temperature, we observed crystalline AMR with two-fold and eight-fold symmetries. In a metallic 100 nm-thick (In,Fe)As layer with higher electron concentration, only two-fold symmetric crystalline AMR was observed. Our results demonstrate the macroscopic ferromagnetism in (In,Fe)As with magnetic anisotropy that depends on the electron concentration. Non-crystalline AMR is also observed in the 100 nm-thick layer, but its magnitude is as small as 10^-5, suggesting that there is no s-d scattering near the Fermi level of (In,Fe)As. We propose the origin of the eight-fold symmetric crystalline anisotropy in (In,Fe)As.
Signatures of dephasing by mirror-symmetry breaking in weak-antilocalization magnetoresistance across the topological transition in Pb$_{1-x}$Sn$_{x}$Se
许多导体，包括最近研究的狄拉克材料，在降低温度时表现出相干长度的饱和。这种令人惊讶的现象归因于外部噪声、残留磁性杂质或特定于非晶态固体的两能级系统。在这里，通过考虑SnTe类化合物作为一个例子，我们从理论上表明，打破镜像对称恶化贝里的相位量化，导致额外的失相弱反局域化磁阻（WAL-MR）。我们的WAL-MR的实验研究证实了这些理论预期在（111）Pb $_{1-x}$ Sn $_x$ Se薄膜与Sn含量$x$对应的拓扑晶体绝缘体和拓扑平凡相。特别是，我们发现故意打破镜像对称性的样品中的相位相干长度的缩短。我们的研究结果表明，量子输运现象的普遍性类的分类应包括，除了时间反演和自旋旋转不变性，在特定的系统中的空间对称性。
Dependence of tunnel magnetoresistance on ferromagnetic electrode materials in MgO-barrier magnetic tunnel junctions
研究了MgO势垒磁性隧道结（MTJ）中隧道磁电阻（TMR）比与电极结构的关系。具有Co 40 Fe 40 B20参考层和自由层的MTJ中的TMR比率在Ta=400摄氏度的沉积后退火温度下达到355%。当Co 50 Fe 50或Co 90 Fe 10用于参考层材料时，没有观察到高TMR比。具有高TMR比的关键是具有高度取向的（001）MgO阻挡层/CoFeB晶体电极。到目前为止，在伪自旋阀MTJ中，在Ta = 450 ℃时获得的最高TMR比为450%。
A phenomenological model for magnetoresistance in granular polycrystalline colossal magnetoresistive materials: the role of spin polarised tunnelling at the grain boundaries
已经观察到，在磁致电阻（CMR）材料的块状和多晶薄膜中，与单晶或低于铁磁转变温度Tc的单晶膜相比，磁阻遵循不同的行为。在本文中，我们发展了一个唯象模型来解释磁场依赖的电阻在颗粒CMR材料考虑到自旋极化隧道在晶界。该模型已被拟合到两个系统，即La 0.55 Ho 0.15 Sr 0.3 MnO 3和La 1.8 Y 0.5 Ca 0.7 Mn 2 O 7。从拟合的结果中，我们已经分离出，在La 0.55Ho 0.15Sr 0.3MnO 3，来自自旋极化隧道在晶界的磁电阻的晶粒间的贡献的内在贡献。结果表明，La_（0.55）Ho_（0.15）Sr_（0.3）MnO_3的本征磁电阻效应随温度的变化符合双交换模型的预测.
Dirac edge states as signature of two-dimensional altermagnetic topological crystalline phase
Universitá degli Studi di Milano（米兰大学）；Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）；International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；SPIN-CNR, UOS Salerno（萨莱诺统一办公室自旋-意大利国家研究委员会）；Consiglio Nazionale delle Ricerche (CNR-SPIN)（意大利国家研究委员会（CNR-SPIN））
Temperature and crystallographic orientation dependence of the anisotropic magnetoresistance in epitaxial Fe65Co35 thin films
Universidad Nacional de Ingeniería（国立工程学院）；Universidad Católica San Pablo（圣保罗天主教大学）；Instituto Balseiro, Universidad Nacional de Cuyo, Comisión Nacional de Energía Atómica（巴尔塞罗研究所，门多萨国立大学，国家原子能委员会）；Instituto de Nanociencia y Nanotecnología (CNEA - CONICET)（纳米科学与技术研究所（国家原子能委员会-国家科学研究和技术委员会））；Comisión Nacional de Energía Atómica（国家原子能委员会）
The discovery of ferromagnetism in two-dimensional (2D) monolayers has stimulated growing research interest in both spintronics and material science. However, these 2D ferromagnetic layers are mainly prepared through an incompatible approach for large-scale fabrication and integration, and moreover, a fundamental question whether the observed ferromagnetism actually correlates with the 2D crystalline order has not been explored. Here, we choose a typical 2D ferromagnetic material, Fe3GeTe2, to address these two issues by investigating its ferromagnetism in an amorphous state. We have fabricate…
Investigation of Hopping Conduction and Its Impact on the Subthreshold and Transition Region Transport in Oxide Semiconductor Transistors by Magneto-Transport Measurements
National Key Laboratory of Advanced Micro and Nano Manufacture Technology and School of Information Science and Electronic Engineering, Shanghai Jiao Tong University（上海交通大学信息科学与电子工程学院）；School of Integrated Circuits, Huazhong University of Science and Technology（华中科技大学集成电路学院）
