Emergent Magnetism and Intrinsic Anomalous Hall Effect in KTaO$_3$ Two-Dimensional Electron Gases

Patrick Krantz, Alex Tyner, Pallab Goswami, Venkat Chandrasekhar

Published 2022-09-21Version 1

There has been intense recent interest in the two-dimensional electron gases (2DEGs) that form at the surfaces and interfaces of KTaO$_3$ (KTO), with the discovery of superconductivity at temperatures significantly higher than those of similar 2DEGs based on SrTiO$_3$ (STO). Here we demonstrate that KTO 2DEGs fabricated under conditions that suppress the superconductivity show emergent magnetism at low temperatures that can be tuned by a gate voltage, V$_g$. The signature of this magnetism is a zero-field transverse voltage that increases in magnitude with decreasing V$_g$, that is strongly asymmetric with respect to an applied perpendicular magnetic field, and that becomes hysteretic in field as the temperature is lowered. We argue that it is due to a finite Berry curvature of the KTO Ta bands in the presence of time-reversal symmetry breaking associated with ordered local moments, with unique features associated with the complex spin texture introduced by spin-orbit interactions in KTO.