Floquet engineering of multi-orbital Mott insulators: applications to orthorhombic titanates

TL;DR

This paper develops a theoretical framework for controlling the magnetic interactions in multi-orbital Mott insulators using laser radiation, enabling tunable spin exchange interactions with minimal heating effects.

Contribution

It derives general expressions for Floquet-driven spin-orbital models and applies them to titanates, demonstrating tunability of magnetic interactions via laser parameters.

Findings

Effective exchange interactions are highly tunable by laser frequency, amplitude, and polarization.

Finite bandwidth and heating effects are considered in the model.

First-principles calculations show significant control over titanates' magnetic properties.

Abstract

We consider driving multi-orbital Mott insulators using laser radiation. We derive general expressions for periodically driven spin-orbital models using time-dependent perturbation theory in the strong interaction limit. We show that the effective exchange interactions of the Floquet spin-orbital Hamiltonian are highly tunable via variations of the frequency, amplitude, and polarization of the laser. We also take the effect of finite bandwidth of excitations into account and study possible heating effects. We further apply our formalism to orthorhombic titanates YTiO$_3$ and LaTiO$_3$ based on first-principles calculations, and find that the spin exchange interactions in these compounds can be engineered to a large extent by tuning the frequency and electric-field amplitude of the laser.