# Temperature driven phase transition at the antimonene/Bi2Se3 van der Waals heterostructure

## TL;DR

This study uncovers a temperature-induced phase transition in antimonene when interfaced with Bi2Se3, showing how annealing favors the eta phase due to substrate interactions, with thermodynamic calculations explaining the stability.

## Contribution

It demonstrates the temperature-driven phase transition in antimonene/Bi2Se3 heterostructures and provides first principles thermodynamics insights into phase stability and transition pathways.

## Key findings

- Annealing causes eta-antimonene to dominate over he ext{alpha} phase.
- The eta phase forms a perfect lattice match with Bi2Se3 after annealing.
- Thermodynamics calculations explain the temperature-dependent stability of phases.

## Abstract

We report the discovery of a temperature induced phase transition between the \alpha and \beta structures of antimonene. When antimony is deposited at room temperature on bismuth selenide, it forms domains of \alpha-antimonene having different orientations with respect to the substrate. During a mild annealing, the \beta phase grows and prevails over the \alpha phase, eventually forming a single domain that perfectly matches the surface lattice structure of bismuth selenide. First principles thermodynamics calculations of this van der Waals heterostructure explain the different temperature-dependent stability of the two phases and reveal a minimum energy transition path. Although the formation energies of free-standing \alpha- and \beta-antimonene only slightly differ, the \beta phase is ultimately favoured in the annealed heterostructure due to an increased interaction with the substrate mediated by the perfect lattice match.