Topological insulator Bi2Se3 films on rare earth iron garnets and their high-quality interfaces

TL;DR

This study demonstrates the successful growth of high-quality Bi2Se3 topological insulator films on rare earth iron garnet magnetic insulators, revealing strong interfacial exchange effects relevant for spintronics and quantum computing.

Contribution

The paper introduces a novel Se-buffered low-temperature growth technique for epitaxial Bi2Se3 on magnetic insulators, enabling high-quality interfaces for the first time.

Findings

High-quality epitaxial Bi2Se3 films on TmIG with excellent crystallinity.

Observation of anomalous Hall effect indicating strong interfacial exchange.

Shift in ferromagnetic resonance field demonstrating magnetic coupling.

Abstract

The integration of quantum materials like topological insulators (TIs) with magnetic insulators (MIs) has important technological implications for spintronics and quantum computing. Here we report excellent crystallinity of c-axis oriented epitaxial TI films Bi2Se3 grown on MI films, a rare earth iron garnet (ReIG), such as thulium iron garnet (Tm3Fe5O12, TmIG) by molecular beam epitaxy (MBE) with a Se-buffered low-temperature (SBLT) growth technique. We demonstrated a streaky reflection high-energy electron diffraction pattern starting from the very first quintuple layer of Bi2Se3, indicating the high-quality interface between TmIG and Bi2Se3, a prerequisite for studying interfacial exchange coupling effects. The strong interfacial exchange interaction was manifested by observations of anomalous Hall effect in the Bi2Se3/TmIG bilayer and a shift of ferromagnetic resonance field of TmIG induced by Bi2Se3. We have reproducibly grown high-quality Bi2Se3/ReIG and interfaces using this new TI growth method, which may be applied to grow other types of van der Waals (vdW) hetero-structures.