Journal Article

PUBDB-2026-02189

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png First-order phase transition driven by competing charge-order fluctuations in 1$T′ − TaTe_2$

Mahatha, S. K. ; Kar, A. ; Corral-Sertal, J. ; Diego, J. ; Korshunov, A. ; Lim, C.-Y. ; Diekmann, F. K. ; Subires, D. ; Phillips, J. ; Kim, T. K. ; Ishikawa, D. ; Marini, G. ; Vobornik, I. ; Errea, I. ; Rohlf, S. ; Kalläne, M. ; Bellini, V. ; Baron, A. Q. R. ; Fumega, A. O. ; Bosak, A. ; Pardo, V. (Corresponding author)Extern*XFEL.EU* ; Rossnagel, K. (Corresponding author)DESY* ; Blanco-Canosa, S. (Corresponding author)Extern*

2026
Inst. Woodbury, NY

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Please use a persistent id in citations: doi:10.1103/xg7k-8tbx

Abstract: First-order phase transitions, characterized by a discontinuous change in the order parameter, are intriguing phenomena in condensed matter physics. However, the underlying, material-specific, microscopic mechanisms often remain unclear. Here, we unveil a high-temperature incommensurate charge-order precursor with the wave vector 𝐪*=(0,14+𝛿,12)in the 1T' phase of TaTe2, which competes with fluctuating high-temperature Ta trimer bonding states at 𝐪CO=(0,13,0). The precursor state follows the temperature dependence of the hidden incommensurability of the quasi-1D nested Fermi surface. In contrast, the low-temperature commensurate charge order at 𝐪CO, characterized by a charge disproportionation of the inequivalent Ta sites, appears to be driven by local chemical bonding. Dynamical lattice calculations identify an imaginary optical mode at 𝐪*, involving an in-plane vibration of the Ta atoms forming a chainlike structure that renormalizes below 𝑇CO. Our experimental and theoretical observations suggest that the controversial first-order phase transition, as captured by phenomenological Ginzburg-Landau theory, results from the competition between two order parameters: one involving Fermi surface nesting and the other involving local chemical bonding.

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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. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. SuperFlat - Interactions, Superconductivity, Catalysis and Topology In Flat Bands (101020833) (101020833)
4. DELIGHT - Discovering light-induced phases by first-principles material design (101052708) (101052708)

Experiment(s):

1. PETRA Beamline P04 (PETRA III)

Appears in the scientific report 2026

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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