Revealing the order parameter dynamics of 1T-TiSe2 during a photoinduced phase transition

TiSe2 is an intriguing material that hosts a charge density wave (CDW) phase below 200K and that becomes superconducting at elevated pressures or by Cu doping. The key to understand the emergence of such correlated behavioris the order parameter, which can be directly accessed by measuring the CDW gap. Here we use time and angular resolved photoelectron spectroscopy (trARPES)  to perturb the CDW phase in TiSe2 and

follow the quench and recovery of the order parameter in real time. The fluence dependence of the gap is discussed and its implication for the CDW formation mechanism are presented.