Special Colloquium20200304- Emerging Phenomena and Competing Orders from Nonequilibrium Dynamics in Strongly Correlated Systems

The short time evolution of a driven initial state in both bosonic and fermionic systems can be exploited to answer fundamental questions in condensed matter physics and strongly correlated systems. The ultrafast pump-probe spectroscopy provides an opportunity to investigate the electronic structure and corresponding dynamics of excited states in materials. More interestingly, the competing orders of the correlated systems can play an important role in the nonequilibrium conditions. Here, two emerging quantum phenomena in the driven strongly correlated systems are discussed. In the x- ray absorption spectroscopy, the core hole effect provides an additional knob to determine the strongly correlated state in equilibrium. In the driven condition, our results discover that the metallic droplet can appear in the insulating state due to the dynamical emerged core hole. On the other hand, in the heavy fermion compound, we investigate the competing orders between Kondo coherence and the localized state under nonequilibrium conditions. The dynamical responses from different phases behave differently and are related to the intrinsic energy scales. Our studies show that the pump-probe technique can be a versatiletool to explore novel quantum phases and competing orders in complex materials.