Finite-temperature topological invariant for higher-order topological insulators
Abstract
We investigate the effects of temperature on the higher-order topological insulators (HOTIs). The finite-temperature topological invariants for the HOTIs can be constructed by generalizing the Resta's polarization for the ground state to the ensemble geometric phase (EGP) for the mixed states, [C.-E. Bardyn, L. Wawer, A. Altland, M. Fleischhauer, and S. Diehl, PhysRevX.8.011035}{Phys. Rev. X 8, 011035 (2018)}]. The EGP is consistent with the Resta's polarization both at zero temperature and at finite temperatures in the thermodynamic limit. {We find that the temperature can change the critical point and thus induces a phase transition from a topologically-trivial phase to a nontrivial phase in a finite-size system, manifesting changes in the winding of the EGP.
Cite
@article{arxiv.2407.19629,
title = {Finite-temperature topological invariant for higher-order topological insulators},
author = {Congwei Lu and Lixiong Wu and Qing Ai},
journal= {arXiv preprint arXiv:2407.19629},
year = {2025}
}