Symmetry-Driven Floquet Engineering in Multivalley SnS

TL;DR

This paper demonstrates how the symmetry of multivalley SnS can be exploited using Floquet engineering with polarized light to control electronic state parity and band properties, advancing quantum material manipulation.

Contribution

It introduces a symmetry-driven approach to Floquet engineering in SnS, enabling deterministic control over Floquet state parity and valley-selective band renormalization.

Findings

Symmetry-driven photoemission selection rules are established for Floquet states.

Parity of Floquet--Bloch states can be fully controlled by light polarization.

Polarization- and valley-selective band renormalization is achieved.

Abstract

Coherent interactions between time-periodic electromagnetic fields and materials offer a powerful platform for engineering light-matter hybrid Floquet states with tailored functionalities. In particular, the ability to manipulate the wavefunction symmetry of such Floquet states has recently emerged as a new frontier in the field of nonequilibrium control of quantum materials. Here, we investigate symmetry-driven Floquet engineering in bulk multivalley semiconductor tin sulfide (SnS) using time-, polarization-, and angle-resolved extreme ultraviolet photoemission spectroscopy, group-theory analysis, and time-dependent density functional theory. We demonstrate that the material's inherent symmetry gives rise to pronounced symmetry-driven photoemission selection rules for both equilibrium bands and light-induced Floquet states, which we probed through nonequilibrium linear dichroism in extreme ultraviolet photoemission. By leveraging the interplay between crystal and driving-light symmetry, we establish deterministic control over the parity of Floquet--Bloch states. Indeed, we show that the symmetry of Floquet--Bloch states can be fully controlled by the relative alignment between the drive polarization and the crystal axes, enabling selective parity inversion with respect to the equilibrium valence and conduction bands. Furthermore, we show that symmetry-driven parity engineering allows for polarization- and valley-selective band renormalization. These findings advance the understanding of guiding principles for wavefunction symmetry engineering, providing pathways for selectively controlling both the parity and renormalization of electronic states in quantum materials using tailored electromagnetic fields.