Hysteretic coherence collapse across the first-order charge density wave transition in
Phys. Rev. B 114, 165132 – Published 23 September, 2026
DOI: https://doi.org/10.1103/q3kc-f99m
Abstract
The first order phase transition between the nearly commensurate (NC-CDW) and commensurate (C-CDW) charge density wave phases in underpins its exotic electronic behavior, yet the spectroscopic evolution of the low energy electronic structure across this transition remains crucial to understand. Using angle resolved photoemission spectroscopy (ARPES), we investigate the low temperature C-CDW phase, characterized by a flat band commonly associated with the lower Hubbard band and a distinct in-gap state located closer to the Fermi level. Photon energy dependent measurements distinguish these two low energy features through their different spectral weight evolution. Temperature dependent ARPES across heating and cooling cycles reveals that the in-gap state undergoes an abrupt collapse upon heating into the NC-CDW phase and re-emerges sharply upon cooling back into the C-CDW phase. This pronounced thermal hysteresis provides direct spectroscopic evidence of the first order nature of the transition. Furthermore, the disappearance and recovery of the in-gap state closely track the corresponding changes in resistivity, highlighting its intimate connection to the electronic reconstruction across the C-CDW–NC-CDW phase transition.
