# Atomic-ordering-induced quantum phase transition between topological crystalline insulator and Z2 topological insulator

## TL;DR

This paper demonstrates that atomic ordering in PbSnTe2 alloy can induce a quantum phase transition between topological crystalline insulator and Z2 topological insulator phases, offering a new way to switch topological states.

## Contribution

It reveals that atomic ordering can be used to electrically switch between TCI and Z2 TI phases in a single material, overcoming previous limitations.

## Key findings

- Atomic ordering in PbSnTe2 induces a phase transition.
- Electrical switching between TCI and Z2 TI phases is possible.
- Atomic ordering provides a new platform for topological phase control.

## Abstract

Topological phase transition in a single material usually refers to transitions between a trivial band insulator and a topological Dirac phase, but the transition may also occur between different classes of topological Dirac phases. However, it is a fundamental challenge to realize quantum transition between Z2 nontrivial topological insulator (TI) and topological crystalline insulator (TCI) in one material because Z2 TI and TCI are hardly both co-exist in a single material due to their contradictory requirement on the number of band inversions. The Z2 TIs must have an odd number of band inversions over all the time-reversal invariant momenta, whereas, the newly discovered TCIs, as a distinct class of the topological Dirac materials protected by the underlying crystalline symmetry, owns an even number of band inversions. Here, take PbSnTe2 alloy as an example, we show that at proper alloy composition the atomic-ordering is an effective way to tune the symmetry of the alloy so that we can electrically switch between TCI phase and Z2 TI phase when the alloy is ordered from a random phase into a stable CuPt phase. Our results suggest that atomic-ordering provides a new platform to switch between different topological phases.

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Source: https://tomesphere.com/paper/1702.05697