Magnetically ordered state at correlated oxide interfaces: the role of random oxygen defects

TL;DR

This study investigates how random oxygen vacancies influence magnetic ordering at correlated oxide interfaces, revealing that vacancies can enhance ferromagnetism and stabilize magnetization, especially in strongly correlated regimes.

Contribution

It introduces a model analyzing the impact of oxygen vacancies on interfacial magnetism, highlighting vacancy-induced ferromagnetism stabilization and nonmonotonic magnetization behavior.

Findings

Vacancies enhance ferromagnetic order.

Magnetization stabilizes above 10% vacancy concentration.

Strong correlations lead to increased magnetic moments.

Abstract

Using an effective one-band Hubbard model with disorder, we consider magnetic states of the correlated oxide interfaces, where effective hole self-doping and a magnetially ordered state emerge due to electronic and ionic reconstructions. By employing the coherent potential approximation, we analyze the effect of random oxygen vacancies on the two-dimensional magnetism. We find that the random vacancies enhance the ferromagnetically ordered state and stabilize a robust magnetization above a critical vacancy concentration of about c=0.1. In the strong-correlated regime, we also obtain a nonmonotonic increase of the magnetization upon an increase of vacancy concentration and a substantial increase of the magnetic moments, which can be realized at oxygen reduced high-Tc cuprate interfaces.