Bilinear magnetoresistance in HgTe topological insulator: opposite signs at opposite interfaces demonstrated by gate control

TL;DR

This paper reports the discovery and control of bilinear magnetoresistance in strained HgTe topological insulators, demonstrating opposite signs at different interfaces and showing potential for spintronic applications.

Contribution

It presents the first observation of tunable bilinear magnetoresistance in HgTe TIs, with a theoretical model explaining the experimental results.

Findings

Bilinear magnetoresistance observed at 1 T magnetic field.

Amplitude and sign of BMR can be controlled via gate voltage.

BMR magnitude exceeds previous measurements in TIs.

Abstract

Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced, bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and sign of this BMR can be tuned by controlling, with an electric gate, the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1 \% and has a larger figure of merit than previously measured TIs. We propose a theoretical model giving a quantitative account of our experimental data. This phenomenon, unique to TI, offers novel opportunities to tune their electrical response for spintronics.