Giant gate-controlled proximity magnetoresistance in semiconductor-based ferromagnetic/nonmagnetic bilayers

TL;DR

This paper reports a giant proximity magnetoresistance of about 80% in NM/FM bilayers with a gate-controlled modulation, significantly larger than previous observations, enabled by wavefunction penetration in semiconductor heterostructures.

Contribution

It introduces a new large magnetoresistance effect in NM/FM bilayers with gate control, demonstrating a novel magnetic-gating spin transistor concept.

Findings

Giant PMR (~80%) observed at 14 T in NM/InAs and (Ga,Fe)Sb bilayers.

PMR magnitude can be tuned by gate voltage.

Wavefunction penetration explains the large PMR effect.

Abstract

The evolution of information technology has been driven by the discovery of new forms of large magnetoresistance (MR), such as giant magnetoresistance (GMR) and tunnelling magnetoresistance (TMR) in magnetic multilayers. Recently, new types of MR have been observed in much simpler bilayers consisting of ferromagnetic (FM)/nonmagnetic (NM) thin films; however, the magnitude of MR in these materials is very small (0.01 ~ 1%). Here, we demonstrate that NM/FM bilayers consisting of a NM InAs quantum well conductive channel and an insulating FM (Ga,Fe)Sb layer exhibit giant proximity magnetoresistance (PMR) (~80% at 14 T). This PMR is two orders of magnitude larger than the MR observed in NM/FM bilayers reported to date, and its magnitude can be controlled by a gate voltage. These results are explained by the penetration of the InAs two-dimensional-electron wavefunction into (Ga,Fe)Sb. The ability to strongly modulate the NM channel current by both electrical and magnetic gating represents a new concept of magnetic-gating spin transistors.