Ultrafast optical control of complex oxide functional properties: New insights from theory and first-principles calculations

Recent experiments have demonstrated the potential for ultrafast changes in the functional properties of materials upon selective optical excitation of particular phonon modes. The chemical diversity of complex oxides, and their strong lattice-properties coupling, have made them ideal test systems for new experimental approaches that exploit anharmonic phonon couplings to induce and modify magnetism, superconductivity and ferroelectricity with light.

In this talk, I will describe our recent theoretical efforts exploring ultrafast optical control of the functional properties of perovskite oxides. I will focus on two examples in particular: dynamical stabilization of a non-equilibrium magnetic phase in GdTiO₃, and transient switching of ferroelastic domains in LaAlO₃ under realistic experimental conditions. Our work highlights the importance of understanding the contributions of small structural distortions to the optical response in perovskites (in contrast with large-amplitude distortions, such as octahedral rotations), and illustrates how, in experiments involving intense resonant excitation of infrared active modes, considering nonlinear contributions to the lattice polarizability can open new pathways to structural control.