The Zintl phase compounds AEIn2As2 (AE = Ca, Sr, Ba): topological phase transition under pressure

Abstract

AEIn₂As₂ (AE = Ca, Sr, Ba), as a new crucial nonmagnetic thermoelectric candidate, needs to be understood in terms of its potential electronic structure properties and topological characteristics in both experimental and theoretical studies. Here we report that AEIn₂As₂ with Zintl phases will undergo insulator–metal phase transition and topological quantum phase transition under pressure modulation based on first-principles calculations. Firstly, band inversion occurred between the In(As)-s and As(In)-p states in the structures of AEIn₂As₂ with the P6₃/mmc space group in the absence of pressure and identified that they are all non-trivial topological insulators. Next, Bader charge and AIM topology analysis elucidate the nature of pressure-induced chemical bond enhancement. Lastly, we have discovered pressure-controllable band gap closure while the topologically protected surface states disappear, realizing insulator–metal phase transition and topological quantum phase transition. Our research not only enriches the family of topological insulators but also provides a good platform for the study of thermoelectric properties.