Time-reversal-breaking topological phases in antiferromagnetic Sr$_2$FeOsO$_6$ films

TL;DR

This paper demonstrates that antiferromagnetic Sr$_2$FeOsO$_6$ films can host time-reversal-breaking topological phases, such as quantum anomalous Hall and chiral topological superconducting states, which can be electrically controlled.

Contribution

It reveals the conditions for realizing topological phases in antiferromagnetic materials and proposes an electrically tunable platform for topological phase transitions.

Findings

Quantum anomalous Hall phase can be realized in Sr$_2$FeOsO$_6$ films.

External electric gate voltage can induce topological phase transitions.

Breaking combined time-reversal and inversion symmetry is essential.

Abstract

In this work, we studied time-reversal-breaking topological phases as a result of the interplay between antiferromagnetism and inverted band structures in thin films of antiferromagnetic double perovskite transition-metal Sr$_2$FeOsO$_6$. By combining the first-principles calculations and analytical models, we demonstrate that the quantum anomalous Hall phase and chiral topological superconducting phase can be realized in this system. We find that to achieve time-reversal-breaking topological phases in antiferromagnetic materials, it is essential to break the combined symmetry of time reversal and inversion, which generally exists in antiferromagnetic structures. As a result, we can utilize an external electric gate voltage to induce the phase transition between topological phases and trivial phases, thus providing an electrically controllable topological platform for the future transport experiments.