# Antiferroelectric topological insulators in orthorhombic $A$MgBi compounds ($A=$ Li, Na, K)

## TL;DR

This paper predicts that certain orthorhombic alkali-MgBi compounds are antiferroelectric topological insulators, where electric fields can control topological phases, with tunable properties via strain and pressure, promising for electronics and spintronics.

## Contribution

The study introduces antiferroelectric topological insulators in orthorhombic $A$MgBi compounds and demonstrates their tunability using strain and pressure through first principles calculations.

## Key findings

- Several alkali-MgBi compounds are predicted to be antiferroelectric topological insulators.
- Epitaxial strain and hydrostatic pressure can tune their topological order and band gaps.
- Electric fields can switch topological phases, enabling potential device applications.

## Abstract

We introduce antiferroelectric topological insulators as a new class of functional materials in which an electric field can be used to control topological order and induce topological phase transitions. Using first principles methods, we predict that several alkali-MgBi orthorhombic members of an $ABC$ family of compounds are antiferroelectric topological insulators. We also show that epitaxial strain and hydrostatic pressure can be used to tune the topological order and the band gap of these $ABC$ compounds. Antiferroelectric topological insulators could enable precise control of topology using electric fields, enhancing the applicability of topological materials in electronics and spintronics.