Transient XUV spectroscopy for revealing many-body physics of correlated materials

In this talk, I will discuss how various element edges display different senstivity towards charge, phonon and polaron dynamics. In particular, I will discuss ultrafast photodynamics of strongly correlated materials and show case how transient XUV is uniquely useful to disentangle these degrees of freedom in these materials. In the first example, we studied TMD monolayer. By comparing with the dynamics of bulk counterparts, we found that while charge localization occurs in the bulk TMD, such loclaization was absent from the monolayer due to the fast charge recombination because of the direct bandgap. In the second example, we focused TeNi2Se5, a potential exciton insulator material. Its transient XUV displays distinct senstivity towards electron, phonon and lattice degrees of freedom, allowing a complete seperation of their dynamics and shed insight to the mechanism of exciton insulator phase transition.