Search

The topological antiferromagnet γ -FeMn is a fascinating material for studying unconventional magnetic properties and topological transport phenomena though high-quality γ -FeMn has been obtained on the Cu substrate for magnetic research. However, the difficulty of growing single-crystalline γ -FeMn films on insulating substrates has prevented experiments from exactly verifying many theoretical predictions on their transport properties. Ultrathin Cu buffer films have been considered for solving this problem but failed because the crystal quality and thickness of Cu films achieved in previous works do not satisfy the growth buffer criteria for γ -FeMn. In this work, the growth of 5-nm-thick Cu films on SrTiO 3 (001) substrates was studied. It was found that single-crystalline ultrathin Cu films with roughness as low as 1 nm are obtained on the insulating substrate. We subsequently obtained high crystalline quality γ -FeMn films with smooth surface and verified their antiferromagnetism. Finally, two aspects of the influence of Cu films on adjacent films have been analyzed. Our results facilitate the experimental exploration of the fascinating properties of γ -FeMn. [ABSTRACT FROM AUTHOR]

Angular-dependent magnetoresistance (ADMR) of an epitaxial Fe(001) film is investigated with current along hard and easy axes in-plane at different temperatures. The temperature dependences of ordinary magnetoresistance (OMR), anisotropic magnetoresistance (AMR), and magnetocrystalline anisotropy magnetoresistance (MMR) in ADMR were determined. As temperature decreases, negative OMR and positive AMR with a twofold symmetry show increasing and decreasing amplitudes, respectively. The amplitude of MMR with twofold and fourfold symmetries is almost invariable with both temperature and magnetic field. Meantime, when current was applied at hard and easy axes, MMR contributes an anti-phase signal to ADMR. Our findings of OMR, AMR, and MMR in the Fe(001) ADMR are of great significance to the understanding of magnetoresistance in magnetic films. [ABSTRACT FROM AUTHOR]

Exchange bias is usually observed in systems with an interface between a ferromagnet and an antiferromagnet. As a result of the competition between antiferromagnetic and ferromagnetic interactions at the interface, this effect may involve aspects of glassy behavior. However, the relationship between spin glass and exchange bias is still under investigation. The formation origin of magnetic anisotropy in spin glasses to reveal their relation is a key research issue. Here, we comparatively study the magnetic and transport exchange bias in a spin glass CuMn after zero-field cooling from an unmagnetized state. We show that the magnetic anisotropy causing the zero-field-cooled exchange bias can be resolved by a linear superposition of unidirectional and uniaxial parts through transport measurements. The former provides a source of net magnetic moments, whereas the latter provides a mechanism for its pinning, which induces the exchange anisotropy for the zero-field-cooled exchange bias during a virgin magnetization process. [ABSTRACT FROM AUTHOR]

An unexpectedly larger current-induced spin–orbit torque in oxidized Cu (CuO x )/ferromagnet (FM) than heavy-metal/FM has recently attracted intense attention in spintronic studies. Although the two mechanisms, interfacial Rashba Edelstein effect and spin-vorticity coupling, have been put forward based on the two different conductive features of CuO x , i.e. electrical insulator and gradient of electrical mobility, the detailed investigation of transport of CuO x is still lacking. Here we experimentally report the positive and negative anomalous Hall effect (AHE) in naturally oxidized normal-metal Al/Cu double films. We found that the onset temperature of AHE corresponds to magnetic transition temperature of CuO x . Furthermore, by comparing Hall resistance of the crystalline and amorphous Cu/Al double films, we identify that the positive anomalous Hall resistance attributes to magnetic moment of CuO x itself, while the negative anomalous Hall resistance can originate from the spin or orbital currents generated at the CuO x /AlO x interface interact with magnetization of CuO x and its inverse process. [ABSTRACT FROM AUTHOR]

Materials with one-dimensional Weyl nodal lines are attracting much attention because of rich exotic properties. In this work, based on the first-principles calculations, we predict the existence of Weyl nodal lines in Fe70Al30. A large intrinsic anomalous Hall conductivity is calculated to be −374 S / cm , which stems from the net Berry curvature induced by Weyl nodal lines. To confirm our calculated results, high quality Fe70Al30 has been prepared and did possess a large anomalous Hall conductivity, where the intrinsic Berry curvature plays a role. [ABSTRACT FROM AUTHOR]

Gilbert damping in epitaxial Heusler Co2FeAl films with thickness varying from 3 nm to 9 nm are investigated by broadband ferromagnetic resonance (FMR) with a temperature range of 5 K–300 K. Gilbert damping shows a continuous decrease with the increasing thickness of Co2FeAl films. Moreover, an enhanced peak of the Gilbert damping is observed with increasing temperature up to approximately 50 K for 3 nm, 6 nm and 9 nm thick Co2FeAl films, which may be attributed to the spin reorientation transition at Co2FeAl/MgO interface. Further, we analyzed the linewidth with a superposition of a uniaxial and a fourfold anisotropy for all samples, which suggests that FMR linewidth in epitaxial Co2FeAl films stems from two-magnon scattering. The change of Gilbert damping is confirmed to originate from various order degrees of the B2 phase with the growth of CFA film, impacting the control of magnetic damping in spin-based nanodevices. [ABSTRACT FROM AUTHOR]