Non-Thermal Pathways to The Origin of a Charge Density Wave
Highly correlated systems host in many cases a complex electronic phase diagram, with different
phases competing or emerging from one-another. A new group of kagome metals AV 3 Sb 5 (A =
K, Rb, Cs) exhibit a variety of intertwined unconventional electronic phases, which emerge from
a puzzling charge density wave phase. Understanding of this parent charge order phase is crucial
for deciphering the entire phase diagram. However, the mechanism of the charge density wave is
still controversial, and its primary source of fluctuations – the collective modes – have not been
experimentally observed. In my talk I will show how we use ultrashort laser pulses to melt the
charge order in CsV 3 Sb 5 and record the resulting dynamics using femtosecond angle-resolved
photoemission. We resolve the melting time of the charge order and directly observe its
amplitude mode, imposing a fundamental limit for the fastest possible lattice rearrangement time.
These observations together with ab-initio calculations provide clear evidence for a structural
rather than electronic mechanism of the charge density wave, providing a path towards better
understanding of the unconventional phases hosted on the kagome lattice.
10:45-11:15 Hadar Steinerg
11:15-12:00 Nadav Katz
13:30-14:30 Lunch with Maxim Khodas
14:30-15:00 Oded Millo
15:00-15:30 Dror Orgad
15:30-16:00 Ronen Rapaport