Dynamical symmetry of strongly light-driven electronic system in crystalline solids

Kohei Nagai,Yasumitsu Miyata,Koichiro Tanaka,Naotaka Yoshikawa,Kento Uchida,Takahiko Endo

doi:10.1038/s42005-020-00399-x

Kohei Nagai, Yasumitsu Miyata + Show 4 more

Open Access

https://doi.org/10.1038/s42005-020-00399-x

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Abstract

The Floquet state, which is a periodically and intensely light-driven quantum state in solids, has been attracting attention as a novel state that is coherently controllable on an ultrafast time scale. An important issue has been to demonstrate experimentally novel electronic properties in the Floquet state. One technique is light scattering spectroscopy, which offers an important clue to clarifying the symmetries and energy structures of the states through symmetry analysis of the polarization selection rules. Here, we determine circular and linear polarization selection rules of light scattering in a mid-infrared-driven Floquet system in monolayer MoS2 and provide a comprehensive understanding in terms of the “dynamical symmetry” of the Floquet state.

Highlights

The Floquet state, which is a periodically and intensely light-driven quantum state in solids, has been attracting attention as a novel state that is coherently controllable on an ultrafast time scale
On the other hand, when the MIR-driving pulses are Y-polarized (Fig. 3f, h), the polarization of the sideband is parallel to that of NIR pulses for all orders. To explain these selection rules, we propose a simple scheme for symmetry analysis of high-order sideband generation (HSG) using the “Raman tensor” and dynamical symmetries” (DSs)
HSG selection rules were explained in terms of the symmetry of microscopic intraband dynamics of electron–hole pairs in momentum space[20]

Summary

Introduction

The Floquet state, which is a periodically and intensely light-driven quantum state in solids, has been attracting attention as a novel state that is coherently controllable on an ultrafast time scale. We systematically present polarization selection rules, which is fundamental to probe the symmetry of the electronic states, for HSG in monolayer MoS2 under a mid-infrared (MIR) driving field. Since we obtained the same result from monolayer MoSe2, which has the same crystal structure, the selection rules are determined only by the symmetry of the crystal and polarization of the light (Supplementary Fig. 2).

Results

Conclusion