Emerging magnetism and electronic phase separation at titanate interfaces

TL;DR

This paper investigates how oxygen vacancies induce magnetism and phase separation at titanate interfaces, revealing complex magnetic behaviors tunable by gate fields and critical defect concentrations.

Contribution

It demonstrates that oxygen vacancies cause unconventional magnetism in titanate interfaces and develops an effective multiorbital model to explain the phenomena.

Findings

Localized vacancies induce ferromagnetic order in the t2g band

Complex magnetic oscillations occur in the eg band

Magnetic states can be tuned by gate fields

Abstract

The emergence of magnetism in otherwise nonmagnetic compounds and its underlying mechanisms have become the subject of intense research. Here we demonstrate that the nonmagnetic oxygen vacancies are responsible for an unconventional magnetic state common for titanate interfaces and surfaces. Using an effective multiorbital modelling, we find that the presence of localized vacancies leads to an interplay of ferromagnetic order in the itinerant t2g band and complex magnetic oscillations in the orbitally-reconstructed eg-band, which can be tuned by gate fields at oxide interfaces. The magnetic phase diagram includes highly fragmented regions of stable and phase-separated magnetic states forming beyond nonzero critical defect concentrations.