Quantum Anomalous Hall and Half-metallic Phases in Ferromagnetic (111) Bilayers of 4d and 5d Transition Metal Perovskites

TL;DR

This study uses first-principles calculations to reveal that certain 4d and 5d transition metal perovskite (111) bilayers exhibit exotic quantum phases like quantum anomalous Hall insulators and half-metals, with potential for advanced electronic applications.

Contribution

It demonstrates, through systematic density functional theory analysis, the emergence of quantum anomalous Hall and half-metallic phases in specific ferromagnetic (111) bilayers of 4d and 5d transition metal perovskites, highlighting their potential for novel quantum phenomena and device use.

Findings

(LaOsO3)2 is a quantum anomalous Hall insulator.

Several bilayers are ferromagnetic with high Curie temperatures.

Some bilayers are half-metallic or exhibit colossal magnetic anisotropy.

Abstract

Extraordinary electronic phases can form in artificial oxide heterostructures, which will provide a fertile ground for new physics and also give rise to novel device functions. Based on a systematic first-principles density functional theory study of the magnetic and electronic properties of the (111) superlattices (ABO3)2/(AB'O3)10 of 4d and 5d transition metal perovskite (B = Ru, Rh, Ag, Re, Os, Ir, Au; AB'O3 = LaAlO3, SrTiO3), we demonstrate that due to quantum confinement, bilayers (LaBO3)2 (B = Ru, Re, Os) and (SrBO3)2 (B = Rh, Os, Ir) are ferromagnetic with ordering temperatures up to room temperature. In particular, bilayer (LaOsO3)2 is an exotic spin-polarized quantum anomalous Hall insulator, while the other ferromagnetic bilayers are metallic with large Hall conductances comparable to the conductance quantum. Furthermore, bilayers (LaRuO3)2 and (SrRhO3)2 are half-metallic, while bilayer (SrIrO3)2 exhibits peculiar colossal magnetic anisotropy. Our findings thus show that 4d and 5d metal perovskite (111) bilayers are a class of quasi-two-dimensional materials for exploring exotic quantum phases and also for advanced applications such as low-power nanoelectronics and oxide spintronics.