Topological Anderson Insulator in Cation-Disordered Cu₂ZnSnS₄

Area of Science:

• Condensed Matter Physics
• Materials Science
• Topological Materials

Background:

• Topological insulators (TIs) exhibit unique electronic properties.
• Disorder in materials can dramatically alter their electronic phases.
• The search for practical realizations of topological phases is ongoing.

Purpose of the Study:

• To identify a real material candidate for a disorder-induced Topological Anderson Insulator (TAI).
• To investigate the electronic band structure and topological properties of disordered Copper-2-Zinc-Tin-Sulfide (Cu2ZnSnS4).

Main Methods:

• High-energy reactive mechanical alloying to create a disordered polymorph of Cu2ZnSnS4.
• Density functional theory (DFT) calculations for band structure analysis.
• Adiabatic continuity arguments to connect with known topological materials.
• Slab geometry band structure calculations to identify surface states.

Main Results:

• A novel polymorph of Cu2ZnSnS4 with significant cation disorder was synthesized.
• DFT calculations revealed an inverted band ordering in the disordered phase, distinct from the ordered phase.
• Evidence suggests this disordered material can be topologically connected to known 3D TIs.
• Robust surface states were predicted, characteristic of topological phases.

Conclusions:

• The disordered Cu2ZnSnS4 polymorph is a strong candidate for a disorder-induced TAI.
• This work demonstrates the potential of disordered multinary compounds for topological applications.
• The study paves the way for understanding and utilizing topological behavior in easily synthesized materials.