Floquet spin textures in optically pumped non-Hermitian surface states

TL;DR

This paper reveals observable Floquet spin textures in non-Hermitian surface states of quantum materials under optical pumping, highlighting complex topological structures and their spectroscopic signatures, bridging solid-state interactions, non-Hermiticity, and light-matter coupling.

Contribution

It introduces the concept of Floquet spin textures in NH topological surface states with magnetic disorder, demonstrating their spectroscopic observability and complex topological features.

Findings

Identification of meron strings, skyrmions, and vortices in energy planes

Observation of Bloch lines and vortex rings in energy-momentum space

Topological polarization effects beyond circular dichroism

Abstract

Optical effects of quantum matter with interaction are key to physics and technology. The class of non-Hermitian (NH) phenomena is mostly explored in cold atoms, photonics, and metamaterials out of equilibrium. Effective NH systems due to interaction in equilibrium solids, however, provide a unique opportunity for realizing light-NH matter hybrids via periodic irradiation. Given NH topological surface states with magnetic disorder, here we reveal spectroscopically observable Floquet spin textures for this hybrid quantum matter: merged meron strings, dichroic skyrmions, and domain structure accompanying vortices in energy planes; Bloch lines and topologically twisted vortex rings distinct from Hopfions in energy-momentum space; topological selectiveness of linear polarization occurs besides circular dichroism. Spectroscopic energy evolution and chemical potential dependence are key ingredients of this open hybrid system. With spin-resolved photoemission spectroscopy, this scenario bears prime physical interest by reaching the crossroad between solid-state interaction effects, non-Hermiticity, and light-matter coupling.