Distinguishing and controlling Mottness in 1T-TaS${}_2$ by ultrafast light

Abstract

Distinguishing and controlling the extent of Mottness is important for materials where the energy scales of the onsite Coulomb repulsion U and the bandwidth W are comparable. Here we report the ultrafast electronic dynamics of 1T-TaS${}_2$ by ultrafast time- and angle-resolved photoemission spectroscopy. A comparison of the electron dynamics for the newly-discovered intermediate phase (I-phase) as well as the low-temperature commensurate charge density wave (C-CDW) phase shows distinctive dynamics. While the I-phase is characterized by an instantaneous response and nearly time-resolution-limited fast relaxation (~200 fs), the C-CDW phase shows a delayed response and a slower relaxation (a few ps). Such distinctive dynamics refect the different relaxation mechanisms and provide nonequilibrium signatures to distinguish the Mott insulating I-phase from the C-CDW band insulating phase. Moreover, a light-induced bandwidth reduction is observed in the C-CDW phase, pushing it toward the Mott insulating phase. Our work demonstrates the power of ultrafast light-matter interaction in both distinguishing and controlling the extent of Mottness on the ultrafast timescale.

References in corpus (4)

• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Ultrafast evolution and transient phases of the prototype out-of-equilibrium Mott-Hubbard material V2O3
• Keldysh space control of charge dynamics in a strongly driven Mott insulator
• Large optical tunability from charge density waves in 1T-TaS${}_2$ under incoherent illumination

Cited by in corpus (1)

• Hidden charge density wave induced shadow bands and ultrafast dynamics of CuTe investigated using time-resolved ARPES