Abstract
We show the ferro-rotational nature of the commensurate charge density wave (CCDW) in and track its dynamic modulations by temperature-dependent and time-resolved electric quadrupole rotation anisotropy-second harmonic generation (EQ RA-SHG), respectively. The ultrafast modulations manifest as the breathing and the rotation of the EQ RA-SHG patterns at three frequencies around the reported single CCDW amplitude mode frequency. A sudden shift of the triplet frequencies and a dramatic increase in the breathing and rotation magnitude further reveal a photoinduced transient CDW phase across a critical pump fluence of .
- Received 2 February 2021
- Revised 4 June 2021
- Accepted 6 August 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.126401
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