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TT: Fachverband Tiefe Temperaturen

TT 54: Correlated Electrons: Charge Order

TT 54.4: Vortrag

Freitag, 21. März 2025, 10:15–10:30, H33

Charge Density Wave Quantum Critical Point under Pressure in 2H-TaSe₂ — •Yuliia Tymoshenko¹, Amir-Abbas Haghighirad¹, Rolf Heid¹, Gaston Garbarino², Luigi Paolasini², and Frank Weber¹ — ¹Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany — ²2European Synchrotron Radiation Facility, 71 avenue des Martyrs, CS 40220, Grenoble 38043, France

Suppression of the ordered state is one of the ways to increase the superconducting (SC) transition temperatures. Materials characterized by charge density waves (CDW) and SC are promising candidates for such studies, since both states can be associated with electron-phonon coupling. Transition metal dichalcogenides (TMD) are prominent examples of such coexisting phases, however, not all such materials show the expected behavior or possess additional mechanisms that complicate an unambiguous interpretation. Here, we report high-pressure X-ray diffraction (XRD) and inelastic X-ray scattering (IXS) measurements of a prototypical transition metal dichalcogenide 2H-TaSe₂ and determine the evolution of the CDW state and its lattice dynamics. We found that the quantum critical point (QCP) of the charge density wave is in close proximity to the reported maximum superconducting transition temperature T_sc = 8.2 K. Ab-initio calculations confirm that 2H-TaSe₂ is a typical example of enhanced superconductivity with suppressed order and can serve as a textbook example for studying superconductivity near the quantum critical point of the CDW.

Keywords: high pressure; charge density wave; xrd; ixs; phonons