Effect of dilute magnetism in a topological insulator

TL;DR

This paper investigates how dilute Gd magnetism affects the electronic and surface properties of a topological insulator, Sb2Te3, revealing the emergence of surface magnetism and maintaining topological surface states.

Contribution

It demonstrates that Gd doping introduces dilute magnetism into Sb2Te3, creating surface magnetism while preserving the topological surface state, providing a new platform for studying magnetism-topology interactions.

Findings

Gd doped Sb2Te3 remains a bulk band-gap material with a topological surface state.

Dilute Gd magnetism induces surface magnetism without destroying topological surface states.

The study combines first principles calculations, magneto-transport, ARPES, and tr-ARPES techniques.

Abstract

Three-dimensional topological insulators (TIs) have emerged as a unique state of quantum matter and generated enormous interests in condensed matter physics. The surfaces of a three dimensional (3D) TI are composed of a massless Dirac cone, which is characterized by the Z2 topological invariant. Introduction of magnetism on the surface of TI is essential to realize the quantum anomalous Hall effect (QAHE) and other novel magneto-electric phenomena. Here, by using a combination of first principles calculations, magneto-transport, angle-resolved photoemission spectroscopy (ARPES), and time resolved ARPES (tr-ARPES), we study the electronic properties of Gadolinium (Gd) doped Sb2Te3. Our study shows that Gd doped Sb2Te3 is a spin-orbit-induced bulk band-gap material, whose surface is characterized by a single topological surface state. We further demonstrate that introducing diluted 4f-electron magnetism into the Sb2Te3 topological insulator system by the Gd doping creates surface magnetism in this system. Our results provide a new platform to investigate the interaction between dilute magnetism and topology in doped topological materials.