Anomalous Hall magnetoresistance in metastable antiferromagnetic FeMn

L L Lang,W J Fan,X P Qiu,S M Zhou

doi:10.1063/1.5079783

Abstract

Anomalous Hall magnetoresistance (AHMR) in single ferromagnetic layers arises from anomalous Hall effect induced spin current and its backflow. Here, we have studied the correlation between AHMR and weak ferromagnetism as well as the antiferromagnetic property in metastable FeMn layers. The ferromagnetic and the antiferromagnetic properties are tuned by the FeMn microstructure through varying the Cu buffer layer thickness. With increasing Cu thickness, both the anomalous Hall angle and the AHMR are suppressed as the content of the parasitic ferromagnet becomes low and the antiferromagnetic order strengthens in FeMn. The exchange bias in Co/FeMn further evidences the evolution of FeMn properties with Cu buffer layer thickness. Our results are in agreement with the theoretical prediction of the AHMR and help the understanding of spin current related phenomena in metastable antiferromagnetic materials.

Highlights

The spin Hall magnetoresistance (SMR) has recently been observed in FM/heavy metal (HM) heterostructures, in which the longitudinal resistivity of the HM layer depends on the orientation of the FM magnetization.[6,7]
In Hanle magnetoresistance (HMR), the spin accumulation and the sheet resistivity depend on the magnitude of the external magnetic field, because the spin relaxation time changes with the external magnetic field.[8]
The longitudinal resistivity in metallic FM layers is controlled by the orientation of the FM magnetization, leading to a new phenomenon, the anomalous Hall magnetoresistance (AHMR)

Summary

Introduction

Studies of magnetoresistance (MR) can be traced back to the discovery of anisotropic magnetoresistance in metallic ferromagnets (FMs) made by William Thomson in 1857.1 The MR family includes anisotropic magnetoresistance, giant magnetoresistance (GMR), and Tunneling magnetoresistance.[2,3,4,5] In particular, the spin Hall magnetoresistance (SMR) has recently been observed in FM/heavy metal (HM) heterostructures, in which the longitudinal resistivity of the HM layer depends on the orientation of the FM magnetization.[6,7] The SMR is due to the absorption and the reflection of spin current at the interface that are controlled by the orientation of the FM magnetization.

Results

Conclusion