(Bottom) An illustration of the two-step light melting of polaron state and CDW phase, as well as the light induced topological phase switches from an axion insulator state to a hidden Weyl phase.
Scientific Achievement
Fluence-dependent photocurrents enable controlled transitions within (TaSe4)2I, shifting it sequentially from a polaronic state to a charge density wave (CDW) state, and ultimately to a concealed Weyl phase.
Significance and Impact
The manipulation of chirality in correlated topological states through ultrafast photoexcitations represents a new control concept inaccessible via conventional experimental techniques like DC transports and static-state spectroscopic measurements.
Research Details
Ultrafast terahertz photocurrent spectroscopy reveals a two-step, non-thermal process of light-induced melting in correlated states, alongside chirality switching.
The longitudinal circular photo-galvanic current detects the chirality of light-induced topological phases.
Phonon emission is observed to be synchronized with the ultrafast phase switching.