Collapse of layer dimerization in the photo-induced hidden state of 1T-TaS2

Date & Facts

Stahl, Quirin and Kusch, Maximilian and Heinsch, Florian and Garbarino, Gaston and Kretzschmar, Norman and Hanff, Kerstin and Rossnagel, Kai and Geck, Jochen and Ritschel, Tobias, Collapse of layer dimerization in the photo-induced hidden state of 1T-TaS2, Nature Communications 11, 1247-- (2020).


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 characterize the hidden quantum state of 1T-TaS2 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 interlayer molecular orbital dimers as a key mechanism for this non-thermal collective transition between two truly long-range ordered electronic crystals.

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