Possible mechanisms of electronic phase separation in oxide interfaces

TL;DR

This paper explores three unconventional mechanisms—density-dependent Rashba spin-orbit coupling, superconducting pairing, and electrostatic confinement—that could cause electronic phase separation in oxide interface 2DEGs, explaining observed inhomogeneities.

Contribution

It introduces three novel mechanisms for electronic phase separation in oxide interfaces, emphasizing the role of density-dependent interactions and potentials.

Findings

Density-dependent Rashba spin-orbit coupling can induce EPS.

Superconducting pairing interactions dependent on density can lead to EPS.

Self-consistent electrostatic confinement can cause EPS in 2DEGs.

Abstract

LaAlO3/SrTiO3 ad LaTiO3/SrTiO3 interfaces are known to host a strongly inhomogeneous (nearly) two-dimensional electron gas (2DEG). In this work we present three unconventional electronic mechanisms of electronic phase separation (EPS) in a 2DEG as a possible source of inhomogeneity in oxide interfaces. Common to all three mechanisms is the dependence of some (interaction) potential on the 2DEG's density. We first consider a mechanism resulting from a sizable density-dependent Rashba spin-orbit coupling. Next, we point out that an EPS may also occur in the case of a density-dependent superconducting pairing interaction. Finally, we show that the confinement of the 2DEG to the interface by a density-dependent, self-consistent electrostatic potential can by itself cause an EPS.