Light-induced Floquet spin-triplet Cooper pairs in unconventional magnets

TL;DR

This paper explores how periodic light can induce and control spin-triplet superconducting states in unconventional magnetic materials with nonrelativistic spin splitting, revealing new dynamical phases.

Contribution

It introduces a Floquet formalism to analyze light-induced spin-triplet pairing in unconventional magnets, highlighting the role of photon-assisted processes and Floquet sidebands.

Findings

Photon processes promote spin-triplet Cooper pairs formation.

Floquet sidebands classify superconducting correlations dynamically.

Light drives can manipulate and probe the symmetry of unconventional magnets.

Abstract

The recently predicted unconventional magnets offer a new ground for exploring the formation of nontrivial spin states due to their inherent nonrelativistic momentum-dependent spin splitting. In this work, we consider unconventional magnets with $d$- and $p$-wave parities, and investigate the effect of time-periodic light drives for inducing the formation of spin-triplet phases in the normal and superconducting states. In particular, we consider unconventional magnets without and with conventional superconductivity under linearly and circularly polarized light drives and treat the time-dependent problem within Floquet formalism, which naturally unveils photon processes and Floquet bands determining the emergent phenomena. We demonstrate that the interplay between unconventional magnetism and light gives rise to a non-trivial light-matter coupling which governs the emergence of Floquet spin-triplet states with and without superconductivity that are absent otherwise. We find that photon-assisted processes promote the formation of spin-triplet densities and spin-triplet Cooper pairs between different Floquet sidebands. More precisely, the Floquet sidebands offer an additional quantum number, the Floquet index, which considerably broadens the classification of superconducting correlations that lead to Floquet spin-triplet Cooper pairs as an entirely dynamical phenomenon due to the interplay between light and unconventional magnetism. Furthermore, we discuss how the number of photons is connected to the symmetry of Cooper pairs and also explore how the distinct light drives can be used to manipulate them and probe the angular symmetry of unconventional magnets. Our results therefore unveil the potential of unconventional magnets for realizing nontrivial light-induced superconducting states.