Amplitude mode-driven ultrafast transition into a hidden state in a thin film of transition metal dichalcogenide
We have investigated the light-induced phase transition into a hidden metastable phase in a charge density wave phase in a layered transition metal dichalcogenide compound, 3R-TaSe2, through the direct excitation of amplitude mode by using intense terahertz pulse sources. Appearance of an insulating-like metastable state is observed, as manifested by the opening of a gap in the optical conductivity spectrum in the terahertz frequency range. The formation of the gap synchronizes with the oscillation of the amplitude mode of the equilibrium CDW, indicating the intimate interplay between the hidden phase and the equilibrium CDW state.
The Univ. of Tokyo (Japan)