Giant odd-parity magnetoresistance from proximity-induced topological states

TL;DR

This study reports a giant odd-parity magnetoresistance up to 1150% in a heterostructure with proximity-induced topological states, revealing new physics and potential for ultrasensitive magnetic sensors.

Contribution

It demonstrates the emergence of tilted topological surface states in alpha Sn via magnetic proximity, leading to unprecedented OMR magnitudes.

Findings

Giant OMR of up to 1150% observed at 1 T

Tilted topological surface states induced in alpha Sn

Boltzmann transport model explains OMR behavior

Abstract

Magnetoresistance typically exhibits even symmetry with respect to the magnetic field, owing to time reversal symmetry (TRS) as dictated by Onsager reciprocity relations. However, in certain systems where TRS is broken, magnetoresistance may acquire an odd component with respect to the magnetic field, referred to as odd parity magnetoresistance (OMR). To date, reported OMR values have been modest, usually restricted to a few tens of percent even under high magnetic fields. Here, we report the discovery of a giant OMR reaching up to 1,150% under a relatively low field of 1 T in a heterostructure composed of 3 nm thick alpha Sn and a ferromagnetic semiconductor, (In,Fe)Sb. Although alpha Sn in this thickness range is a trivial narrow gap semiconductor, analysis of Shubnikov de Haas oscillations combined with ab initio calculations reveals the emergence of tilted topological surface states, induced via magnetic proximity from the (In,Fe)Sb layer. The observed OMR behavior is well explained by a Boltzmann transport model assuming the presence of oppositely tilted Weyl cones in the alpha Sn band structure. Our findings not only shed new light on the physics of OMR but also suggest promising avenues for its application in electronic and spintronic devices, such as ultrasensitive magnetic sensors.