Oxygen vacancy-induced anomalous Hall effect in a nominally non-magnetic oxide

TL;DR

This study demonstrates the emergence of an anomalous Hall effect in nominally non-magnetic KTaO3 due to oxygen vacancies, revealing a transition from extrinsic to intrinsic behavior linked to Berry curvature effects.

Contribution

It provides the first evidence of anomalous Hall effect in a non-magnetic oxide driven by oxygen vacancy-induced magnetization and Berry curvature.

Findings

Anomalous Hall effect observed in reduced KTaO3.

Transition from extrinsic to intrinsic Hall effect with temperature.

Berry curvature dominates the Hall response at low temperatures.

Abstract

The anomalous Hall effect, a hallmark of broken time-reversal symmetry and spin-orbit coupling, is frequently observed in magnetically polarized systems. Its realization in non-magnetic systems, however, remains elusive. Here, we report on the observation of anomalous Hall effect in nominally non-magnetic KTaO3. Anomalous Hall effect emerges in reduced KTaO3 and shows an extrinsic to intrinsic crossover. A paramagnetic behavior is observed in reduced samples using first principles calculations and quantitative magnetometry. The observed anomalous Hall effect follows the oxygen vacancy-induced magnetization response, suggesting that the localized magnetic moments of the oxygen vacancies scatter conduction electrons asymmetrically and give rise to anomalous Hall effect. The anomalous Hall conductivity becomes insensitive to scattering rate in the low temperature limit (T<5 K), implying that the Berry curvature of the electrons on the Fermi surface controls the anomalous Hall effect. Our observations describe a detailed picture of many-body interactions, triggering anomalous Hall effect in a non-magnetic system.