The 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 coupling to other phonons. Complex oxide ceramics provide an important test-ground for this experimental approach due to their diversity, strong coupling to optical fields, and demonstrated connection between subtle structural changes and functional properties.
Our recent theoretical efforts in perovskite oxides explore selective control of functional properties that exploit nonlinear lattice dynamics induced by the excitation of infrared phonons. Using first-principles techniques we predict that ultrafast optical control of magnetism is experimentally accessible in rare-earth titanates and show that, when combined with strain, this optical technique exposes a magnetic phase inaccessible in the equilibrium phase diagram.