Interface electronic structure at the topological insulator - ferrimagnetic insulator junction

TL;DR

This study investigates the electronic interface between a topological insulator (Bi2Se3) and a ferrimagnetic insulator (YIG), revealing the surface state and localized Fe 3d states, and discussing the proximity effect and potential Curie temperature enhancement.

Contribution

It provides direct experimental evidence of the interface electronic structure and spin states at the TI-ferrimagnetic insulator junction, highlighting the exchange interaction and ways to enhance magnetic properties.

Findings

Direct observation of Bi2Se3 surface state.

Confirmation of localized Fe 3d spin states in YIG.

Proximity effect mediated by exchange interaction.

Abstract

An interface electron state at the junction between a three-dimensional topological insulator (TI) film of Bi2Se3 and a ferrimagnetic insulator film of Y3Fe5O12 (YIG) was investigated by measurements of angle-resolved photoelectron spectroscopy and X-ray absorption magnetic circular dichroism (XMCD). The surface state of the Bi2Se3 film was directly observed and localized 3d spin states of the Fe3+ state in the YIG film were confirmed. The proximity effect is likely described in terms of the exchange interaction between the localized Fe 3d electrons in the YIG film and delocalized electrons of the surface and bulk states in the Bi2Se3 film. The Curie temperature (TC) may be increased by reducing the amount of the interface Fe2+ ions with opposite spin direction observable as a pre-edge in the XMCD spectra.