Strongly correlated systems exhibit intriguing properties caused by intertwined microscopic in- teractions that are hard to disentangle in equilibrium. Employing non-equilibrium time-resolved photoemission spectroscopy on the quasi-two-dimensional transition-metal dichalcogenide 1T-TaS2, we identify a spectroscopic signature of double occupied sites (doublons) that are reflects fundamental Mott physics. Doublon-hole recombination is estimated to occur on time scales of one electronic hopping cycle ℏ/J≈ 14 fs. Despite strong electron-phonon coupling the dynamics can be explained by purely electronic effects captured by the single band Hubbard model, where thermalization is fast in the small-gap regime. Qualitative agreement with the experimental results however requires the assumption of an intrinsic hole-doping. The sensitivity of the doublon dynamics on the doping level provides a way to control ultrafast processes in such strongly correlated materials.
@article{arxiv.1702.05300,
title = {Ultrafast doublon dynamics in photo-excited 1T-TaS$_2$},
author = {Manuel Ligges and Isabella Avigo and Denis Golež and Hugo Strand and Ljupka Stojchevska and Matthias Kalläne and Ping Zhou and Kai Rossnagel and Martin Eckstein and Philipp Werner and Uwe Bovensiepen},
journal= {arXiv preprint arXiv:1702.05300},
year = {2018}
}