Large nonlinear Hall effect in (FeCo)0.67Ge0.33/Ge heterojunctions

Juan Pei,Ai-Chun Yang,Kun Zhang,Huan-Huan Li,Shu-Qin Xiao,Shi-Shen Yan,Shi-Shou Kang,Li-Min He,You-Yong Dai

doi:10.1142/s0217979219501212

Juan Pei, Ai-Chun Yang + Show 7 more

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https://doi.org/10.1142/s0217979219501212

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Abstract

The large nonlinear Hall effect was found in (FeCo)[Formula: see text]Ge[Formula: see text]/Ge heterojunctions formed by sputtering amorphous [Formula: see text]-type (FeCo)[Formula: see text]Ge[Formula: see text] magnetic semiconductor films on near intrinsic n-type Ge substrate. It is very interesting that the mechanisms of the large nonlinear Hall effect in (FeCo)[Formula: see text]Ge[Formula: see text]/Ge heterojunctions are different at different temperature ranges. Below 10 K, the Hall resistance of (FeCo)[Formula: see text]Ge[Formula: see text]/Ge heterojunctions is almost the same as the anomalous Hall effect of (FeCo)[Formula: see text]Ge[Formula: see text] ferromagnetic films. While the temperature increased from 10 to 60 K, the nonlinear Hall resistance, longitudinal conductance, and magnetoresistance all increased quickly and reached the maximum at T[Formula: see text]=[Formula: see text]60 K. In this case, thermally excited conducting carriers can tunnel through the interfacial potential barrier in (FeCo)[Formula: see text]Ge[Formula: see text]/Ge heterojunctions. Thus, in the range of 10–60 K, the enhanced nonlinear Hall resistance can be attributed to the anomalous Hall effect which was further enhanced by interfacial Rashba spin–orbit coupling effect. When the temperature further increased from 60 to 250 K, the interfacial potential barrier weakened gradually, and the Hall resistance and magnetoresistance decreased due to the shunting of the Ge substrate. In this case, the nonlinear Hall effect of (FeCo)[Formula: see text]Ge[Formula: see text]/Ge heterojunctions can be explained very well by the two-band model of nonlinear Hall effect.

Highlights

Hall effect consistently plays an important role in condensed matter physics for their applications in the fundamental physics and engineering technologies
It is very interesting that the mechanisms of the large nonlinear Hall effect in (FeCo)0.67Ge0.33/Ge heterojunctions are different at different temperature ranges
In the temperature from 10 to 60 K, the enhanced nonlinear Hall resistance can be attributed to anomalous Hall effect (AHE) which was further enhanced by interfacial Rashba spin–orbit coupling effect

Summary

Introduction

Hall effect consistently plays an important role in condensed matter physics for their applications in the fundamental physics and engineering technologies. The first viewpoint attributed the nonlinear Hall effect to the OHE, which held two types of carriers with different densities and/or mobility participated in the magnetotransport, such as in GeMn/Ge and Bi2Se3/YIG heterojunctions.[10,11,12] this model overlooked the influence of interfacial potential barrier on the magnetotransport in heterojunctions. Alegria et al.[14] tried to use AHE and two-band model to investigate the high field nonlinear Hall effect in their Bi2Te3/Cr2Ge2Te6 heterojunctions, respectively, and found both models resulted in nearly identical predictions for Rxy(B). Until now, it is unknown whether the two-band model, or Rashba spin–orbit coupling of interface, or the above two mechanisms contributes together. It is important to investigate the mechanisms of the nonlinear Hall effect in heterostructures

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