Abstract
We investigate the quench and real-time formation of the Mott state and photoexcited carrier relaxation dynamics in the Mott insulator and the superconductor using three-pulse femtosecond optical spectroscopy, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene. In both salts, we find that transient reflectivity amplitude gradually recovers with time after strong near-infrared pulse quench, but its relaxation time is nearly constant throughout. This indicates that in -Cl, the energy gap for charge excitations is filled rather than closed by photoinduced carriers of only % per dimer. The Mott state is re-formed on a few-picosecond timescale with the disappearance of the in-gap photodoping-induced states near the Fermi energy. In -Br, a behavior similar to that in -Cl is observed and attributed to the disorder-induced phase-separated Mott insulating regions.
- Received 1 July 2021
- Revised 15 September 2021
- Accepted 16 September 2021
DOI:https://doi.org/10.1103/PhysRevB.104.115152
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