Photoinduced topological phase transition in monolayer Ti$_2$SiCO$_2$
Abstract
The TiSiCO-family monolayer CO(=Ti, Zr, Hf; =Si, Ge) is a two-dimensional second-order topological insulator with unique valley-layer coupling in equilibrium condition. In this work, based on the four-band tight-binding (TB) model of monolayer TiSiCO (ML-TiSiCO) and the Floquet theory, we study the non-equilibrium properties of the ML-TiSiCO under a periodic field of laser and a gate-electric field. We find the interaction between the time-periodic polarized light and the electric field can lead to a variety of intriguing topological phase transitions. By driving the system with only circularly polarized light (CPL), a photoinduced topological phase transition occurs from a second-order topological insulator to a Chern insulator with a Chern number of 2, and the sign of the Chern number is determined by the chirality of the incident light. Further adding a perpendicular electric field, we find that the ML-TiSiCO exhibits a rich phase diagram, consisting of Chern insulators with different Chern numbers and various topological semimetals. In contrast, since the linearly polarized light (LPL) does not break time-reversal symmetry, the Chern number of the system would not be changed under the irradiation of LPL. However, there still exist many topological phases, including second-order topological insulator, topological semi-Dirac, Dirac and valley-polarized Dirac semimetals under the interaction between the LPL and the electric field. Our results not only enhance the understanding of the fundamental properties of ML-TiSiCO but also broaden the potential applications of such materials in optoelectronic devices.
Keywords
Cite
@article{arxiv.2312.14639,
title = {Photoinduced topological phase transition in monolayer Ti$_2$SiCO$_2$},
author = {Pu Liu and Chaoxi Cui and Zhi-Ming Yu},
journal= {arXiv preprint arXiv:2312.14639},
year = {2023}
}