Abstract
The emergence of photo-induced topological phases and their phase transitions are theoretically predicted in organic salt $\alpha$-(BEDT-TTF)$_2$I$_3$, which possesses inclined Dirac cones in its band structure. By analyzing a photo-driven tight-binding model describing conduction electrons in the BEDT-TTF layer using the Floquet theorem, we demonstrate that irradiation with circularly polarized light opens a gap at the Dirac points, and the system eventually becomes a Chern insulator characterized by a quantized topological invariant. A rich phase diagram is obtained in plane of amplitude and frequency of light, which contains Chern insulator, semimetal, and normal insulator phases. We find that the photo-induced Hall conductivity provides a sensitive means to detect the predicted phase evolutions experimentally. This work contributes towards developing the optical manipulation of electronic states in matter through broadening the range of target materials that manifest photo-induced topological phase transitions.
Highlights
Photoinduced phase transitions are one of the central topics in recent condensed-matter physics [1,2,3,4,5]
By analyzing a photodriven tight-binding model describing conduction electrons in the BEDT-TTF layer using the Floquet theorem, we demonstrate that irradiation with circularly polarized light opens a gap at the Dirac points, and the system eventually becomes a Chern insulator characterized by a quantized topological invariant
A theoretical study using the Floquet theorem has predicted that the honeycomb lattice irradiated with circularly polarized light attains a topological band structure similar to the band structure originally proposed by Haldane [6] that exhibits a topological phase transition
Summary
Photoinduced phase transitions are one of the central topics in recent condensed-matter physics [1,2,3,4,5]. A theoretical study using the Floquet theorem has predicted that the honeycomb lattice irradiated with circularly polarized light attains a topological band structure similar to the band structure originally proposed by Haldane [6] that exhibits a topological phase transition This transition results in the photoinduced quantum Hall effect in graphene, even in the absence of an external magnetic field [7,8], and was confirmed in a recent experiment [9]. One promising material is an organic salt α-(BEDT-TTF)2I3, where BEDT-TTF denotes bis(ethylenedithio)-tetrathiafulvalene [31] This compound has inclined Dirac cones in its band structure [32,33,34], and many interesting topological properties and phenomena rising from these Dirac-cone bands have been theoretically investigated so far, e.g., the quantum Hall effect [32], the structures of Berry curvature in momentum space [35], and the flux-induced Chern insulator phases [36]. This field by expanding the potential range of materials for research
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