Enormous Berry-Curvature-Driven Anomalous Hall Effect in Topological Insulator (Bi,Sb)2Te3 on Ferrimagnetic Europium Iron Garnet beyond 400 K

TL;DR

This study demonstrates a giant anomalous Hall effect in topological insulator/ferromagnetic insulator heterostructures at temperatures exceeding 400 K, driven by Berry curvature and interface engineering, surpassing previous records.

Contribution

It reports the first observation of an enormous Berry-curvature-driven anomalous Hall effect in (Bi,Sb)2Te3 on EuIG at temperatures above 400 K, with insights from first-principles calculations.

Findings

RAHE exceeds 8 Ω at 300 K, sustaining to 400 K

No sign change in AHE loops with chemical potential variation

Observation of topological Hall effect at low temperatures

Abstract

To realize the quantum anomalous Hall effect (QAHE) at elevated temperatures, the approach of magnetic proximity effect (MPE) was adopted to break the time-reversal symmetry in the topological insulator (Bi0.3Sb0.7)2Te3 (BST) based heterostructures with a ferrimagnetic insulator europium iron garnet (EuIG) of perpendicular magnetic anisotropy. Here we demonstrate phenomenally large anomalous Hall resistance (RAHE) exceeding 8 {\Omega} (\r{ho}AHE of 3.2 {\mu}{\Omega}*cm) at 300 K and sustaining to 400 K in 35 BST/EuIG samples, surpassing the past record of 0.28 {\Omega} (\r{ho}AHE of 0.14 {\mu}{\Omega}*cm) at 300 K. The remarkably large RAHE as attributed to an atomically abrupt, Fe-rich interface between BST and EuIG. Importantly, the gate dependence of the AHE loops shows no sign change with varying chemical potential. This observation is supported by our first-principles calculations via applying a gradient Zeeman field plus a contact potential on BST. Our calculations further demonstrate that the AHE in this heterostructure is attributed to the intrinsic Berry curvature. Furthermore, for gate-biased 4 nm BST on EuIG, a pronounced topological Hall effect (THE) coexisting with AHE is observed at the negative top-gate voltage up to 15 K. Interface tuning with theoretical calculations has opened up new opportunities to realize topologically distinct phenomena in tailored magnetic TI-based heterostructures.