Berry phase engineering at oxide interfaces

TL;DR

This paper demonstrates how interface engineering in oxide heterostructures, specifically SrRuO3, can manipulate Berry curvature and the anomalous Hall effect, enabling control of emergent electrodynamics for spintronics and topological electronics.

Contribution

It shows that interface reconstruction in oxide heterostructures can tune Berry curvature and the AHE through competition between topologically non-trivial bands.

Findings

Two interface-tunable spin-polarized conduction channels identified.

AHE tunability linked to competition between non-trivial bands.

Interface engineering enables control of emergent electrodynamics.

Abstract

Geometric phases in condensed matter play a central role in topological transport phenomena such as the quantum, spin and anomalous Hall effect (AHE). In contrast to the quantum Hall effect - which is characterized by a topological invariant and robust against perturbations - the AHE depends on the Berry curvature of occupied bands at the Fermi level and is therefore highly sensitive to subtle changes in the band structure. A unique platform for its manipulation is provided by transition metal oxide heterostructures, where engineering of emergent electrodynamics becomes possible at atomically sharp interfaces. We demonstrate that the Berry curvature and its corresponding vector potential can be manipulated by interface engineering of the correlated itinerant ferromagnet SrRuO$_3$ (SRO). Measurements of the AHE reveal the presence of two interface-tunable spin-polarized conduction channels. Using theoretical calculations, we show that the tunability of the AHE at SRO interfaces arises from the competition between two topologically non-trivial bands. Our results demonstrate how reconstructions at oxide interfaces can be used to control emergent electrodynamics on a nanometer-scale, opening new routes towards spintronics and topological electronics.