Photoinduced topological phase transitions in strained black phosphorus

TL;DR

This study demonstrates how circularly polarized laser irradiation can induce and control topological phase transitions in strained black phosphorus, revealing new nonequilibrium electronic states with potential optoelectronic applications.

Contribution

It introduces a combined Floquet theory and first-principles approach to engineer and analyze photoinduced topological phases in black phosphorus under strain, highlighting tunable Floquet-Dirac states.

Findings

Identification of Floquet-Dirac semimetals and topological insulators.

Tunable topological phase transition from type-I to type-II Floquet-Dirac fermions.

Observation of topological surface states with helicity-locked electron transport.

Abstract

Photoinduced topological phase transitions (TPTs) in black phosphorous (BP) under compressive strain were investigated by combining Floquet theory and first-principles calculations. Intriguing photo-dressed electronic states including Floquet-Dirac semimetals and Floquet topological insulators have been identified, which can be feasibly engineered by changing the direction, intensity and frequency of incident laser. Remarkably, tunable TPT from type-I to type-II Floquet-Dirac fermions can be realized by irradiating circularly polarized laser (CPL), with an origin rooted in optical Stark effect. Furthermore, the photoinduced Floquet-Dirac phases is shown to host topological surface states that exhibit nonequilibrium electron transport in a direction locked by the helicity of CPL. This work provides useful guidance for experimental observation of Floquet TPTs, and extends optoelectrionic applications of BP to nonequilibrium regime.