Dresden 2020 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 70: Correlated Electrons: Charge Order

TT 70.2: Talk

Friday, March 20, 2020, 09:45–10:00, HSZ 103

Collapse of layer-dimerization in 1T-TaS2 — Quirin Stahl¹, Maximilian Kusch¹, Gaston Garbarino², Norman Kretzschmar², Kerstin Hanff³, Kai Rossnagel³, Jochen Geck¹, and •Tobias Ritschel¹ — ¹TU Dresden — ²ESRF, Grenoble — ³CA Universität zu Kiel

Photo-induced switching between collective quantum states of matter is a fascinating rising field with exciting opportunities for novel technologies. Presently very intensively studied examples in this regard are nanometer-thick single crystals of the layered material 1T-TaS2, where picosecond laser pulses can trigger a fully reversible insulator-to-metal transition (IMT). This IMT is believed to be connected to the switching between metastable collective quantum states, but the microscopic nature of this so-called hidden quantum state remained largely elusive up to now. Here we determine the latter by means of state-of-the-art x-ray diffraction and show that the laser-driven IMT involves a marked rearrangement of the charge and orbital order in the direction perpendicular to the TaS₂-layers. More specifically, we identify the collapse of inter-layer molecular orbital dimers, which are a characteristic feature of the insulating phase, as a key mechanism for the non-thermal IMT in 1T-TaS2, which indeed involves a collective transition between two truly long-range ordered electronic crystals.