Shedding light on materials out of equilibrium: Ultrafast control of magnetism in complex oxide thin-films

The recent development of intense ultrashort mid- and far-infrared laser sources has created an opportunity for functional materials based on the direct excitation of infrared active phonons. Strong excitation of infrared active phonons can produce sizable unidirectional distortions of crystal structure through non-linear couplings between various lattice modes. Complex oxides provide an important test-ground for this experimental approach due to their chemical diversity, strong coupling to optical fields, and demonstrated connection between subtle structural changes and functional properties. Early experiments in complex oxides are intriguing, suggesting that non-linear phonon coupling is responsible for transiently induced insulator-metal phase transitions and enhanced superconductivity in optical experiments.
In this talk, I will describe our recent theoretical efforts exploring selective control of functional properties in perovskite oxides that exploit non-linear lattice dynamics. Using first-principles techniques we show that optical control of various properties is experimentally feasible and that, when combined with epitaxial strain, it is possible to transiently stabilize and explore phases inaccessible in the equilibrium phase diagram.