Ultrafast electronic structure engineering in 1 T − TaS 2 : Role of doping and amplitude mode dynamics

In strongly correlated transition metal dichalcogenides, an intricate interplay of polaronic distortions, stacking arrangement, and electronic correlations determines the nature of the insulating state. Transient changes in pristine and Mo-doped 1 T − TaS 2 are measured by femtosecond time-resolved photoelectron spectroscopy and modeled using nonequilibrium dynamical mean-field theory complemented by density functional theory. Inspired by vibrational spectroscopy we analyze real-time oscillatory spectral changes induced by the charge density wave amplitude mode through modulations of electronic interactions. We distinguish effects induced by electron doping and structural disorder which can modify the layer stacking and conclude that doped crystals might feature an enhanced fraction of monolayers. Our work establishes substitutional doping as a pathway to engineer the dynamic electronic structure in correlated transition metal dichalcogenides.