Probing THz magnetic optical response in two-dimensional correlated Mott insulator using time-dependent Wannier functions

The study of light-matter coupling is of great theoretical and experimental interest, between its potential to create new non-equilibrium states and ability to experimentally probe unconventional quantum phases. Unlike conventional THz spectroscopy, which relies on coupling spins to magnetic fields, we demonstrate another mechanism for spin-photon coupling in correlated insulators due to poor electron localization bounded by quantum geometry. Here, photons may excite a magnetic response by perturbing the wavefunction shape of local moments via a THz electric field. We evaluate the optical conductivity in two-dimensional Mott insulators while accounting for the time-dependent deformation of the Wannier functions [1]. We discuss ramifications on realistic materials with non-trivial quantum geometry.

[1] W. T. Tai and M. Claassen, Quantum-Geometric Light-Matter Coupling in Correlated Quantum Materials, arXiv:2303.01597.