This article reports a comparative study of bulk and surface properties in the transition metal dichalcogenide 1T-TaS2. When heating the sample, the surface displays an intermediate insulating phase that persists for ∼10 K on top of a metallic bulk. The weaker screening of Coulomb repulsion and stiffer Charge Density Wave (CDW) explain such resilience of a correlated insulator in the topmost layers. Both time resolved ARPES and transient reflectivity are employed to investigate the dynamics of electrons and CDW collective motion. It follows that the amplitude mode is always stiffer at the surface and displays variable coupling to the Mott-Peierls band, stronger in the low temperature phase and weaker in the intermediate one.
@article{arxiv.2307.06444,
title = {Dynamics of electronic states in the insulating Intermediate surface phase of 1T-TaS$_2$},
author = {Jingwei Dong and Weiyan Qi and Dongbin Shin and Laurent Cario and Zhesheng Chen and Romain Grasset and Davide Boschetto and Mateusz Weis and Pierrick Lample and Ernest Pastor and Tobias Ritschel and Marino Marsi and Amina Taleb and Noejung Park and Angel Rubio and Evangelos Papalazarou and Luca Perfetti},
journal= {arXiv preprint arXiv:2307.06444},
year = {2023}
}