Ultrafast optical switching to a metallic state via photoinduced Mott transition in few-layer MoS2 under hydrostatic pressure

Abstract

Photoinduced Mott transition has been revealed as a superior method to control the optical and electronic properties in excited semiconductors on ultrashort timescales but the corresponding ultrafast carrier dynamics and the underlying many-body interactions, together with their responses to external stimuli besides optical excitation, are still poorly understood. Herein, we experimentally demonstrate that the photoinduced Mott transition in few-layer ${\mathrm{MoS}}_{2}$ at room temperature can be achieved and subtly tuned under mild optical excitation via hydrostatic pressure. Utilizing ultrafast pump-probe spectroscopy, significant reduction of the Mott density by more than two orders of magnitude and a gradual acceleration of the optical switching to the metallic electron-hole plasma state under elevated pressures up to $\ensuremath{\sim}3$ GPa are experimentally revealed, which can be attributed to the reduction of the exciton binding energy and the acceleration of the exciton dissociation under hydrostatic pressure.