  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.
