Quantum Materials from the Dynamical Perspective

Quantum materials are systems in which electronic ground states emerge from strong interactions between charge, spin, lattice, and orbital degrees of freedom. These interactions may be enhanced by reduced dimensionality or geometric frustration, and may also result in topologically protected electronic states. Noninteracting single band models fail to adequately describe these systems. Time-resolved optical measurements using femtosecond laser pulses can be used to study strongly interacting degrees of freedom on their natural timescales. By photoexciting the samples gently, it is possible to study these dynamics without disturbing the underlying order. In this work, the relaxation dynamics of photoexcited quasiparticles are studied in several quantum materials in which Coulomb repulsion and spin-orbit coupling are both strong. The relaxation dynamics reveal information about the low energy energy electronic structure as well as the nature of the strong interactions that govern the emergent properties of the system