Journal Article

PUBDB-2026-00459

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Charge-density-wave quantum critical point under pressure in 2H-TaSe$_2$

Tymoshenko, Y. ; Haghighirad, A.-A. (Corresponding author)Extern* ; Heid, R. ; Lacmann, T. ; Ivashko, A. ; Merritt, A. ; Shen, X. ; Merz, M. ; Garbarino, G. ; Paolasini, L. ; Bosak, A. ; Diekmann, F. K. ; Rossnagel, K.DESY* ; Rosenkranz, S. ; Said, A. H. ; Weber, F. (Corresponding author)Extern*

2025
Springer Nature London

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Please use a persistent id in citations: doi:10.1038/s42005-025-02254-3  doi:10.3204/PUBDB-2026-00459

Abstract: The presence of a quantum-critical point (QCP) at which a nearby ordered phase is suppressed to zero temperature is often invoked to explain emergent quantum phases, e.g. superconductivity. Yet, identifying a QCP and establishing its correlation with superconductivity remains challenging. Materials featuring charge-density-wave (CDW) order and superconductivity offer a clear scenario as both states can be associated with electron-phonon coupling. Here, we uncover a CDW-QCP and demonstrate its interrelation with superconductivity in the prototypical transition-metal dichalcogenide 2H-TaSe$_2$. We determine the evolution of the CDW state up to and beyond its suppression at the critical pressure p$_c$ = 19.9(1) GPa by means of X-ray diffraction and inelastic X-ray scattering measurements providing a full crystallographic refinement of the commensurate CDW superstructure. The pressure-induced CDW-QCP in close vicinity to the maximum superconducting transition temperature. Ab-initio lattice dynamical calculations corroborate that 2H-TaSe$_2$ features order-parameter fluctuation enhanced superconductivity and can serve as a paradigm to investigate superconductivity near a CDW-QCP.

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Contributing Institute(s):

1. FS-SXQM (FS-SXQM)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. DFG project G:(GEPRIS)460248799 - DAPHNE4NFDI - DAten aus PHoton- und Neutronen Experimenten für NFDI (460248799) (460248799)
3. DFG project G:(GEPRIS)444821420 - Elastische Kontrolle von konkurrierenden Ordnungen in korrelierten Quantenmaterialien (B03) (444821420) (444821420)
4. 05K22VK1 - Parabolische geschachtelte Spiegeloptik für thermische Neutronen am Dreiachsenspektrometer PUMA (BMBF-05K22VK1) (BMBF-05K22VK1)

Experiment(s):

1. Measurement at external facility

Appears in the scientific report 2025

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