Topological Anderson Insulator in cation-disordered Cu2ZnSnS4

TL;DR

This study presents experimental and theoretical evidence for a disorder-induced Topological Anderson Insulator phase in cation-disordered Cu2ZnSnS4, revealing robust surface states and surface-dominated transport.

Contribution

First experimental demonstration of a disorder-induced Topological Anderson Insulator in a real material system using Cu2ZnSnS4 with high cation disorder.

Findings

Disordered Cu2ZnSnS4 exhibits inverted band ordering.

Presence of robust surface states confirmed by band structure calculations.

Surface-dominated transport observed experimentally.

Abstract

Abstract: Using ab initio calculations supported by experimental transport measurements, we present the first credible candidate for the realization of a disorder-induced Topological Anderson Insulator in a real material system. High energy reactive ball-milling produces a polymorph of Cu2ZnSnS4 with high cation disorder, which shows an inverted ordering of bands at the Brillouin zone center, in contrast to its ordered phase. Adiabatic continuity arguments establish that this disordered Cu2ZnSnS4 can be connected to the closely related Cu2ZnSnSe4, previously predicted to be a 3D topological insulator. Band structure calculations with a slab geometry reveal the presence of robust surface states, while impedance spectroscopy coupled with resistivity measurements point to the surface-dominated transport which such states would imply; thus making a strong case in favor of a novel topological phase. As such, this study opens up a window to understanding and potentially exploiting topological behavior in a rich class of easily-synthesized multinary, disordered compounds.