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Soft-Phonon and Charge-Density-Wave Formation in Nematic BaNi₂As₂

Souliou, S. M. 1; Lacmann, T. ORCID iD icon 1; Heid, R. 1; Meingast, C. 1; Frachet, M. 1; Paolasini, L.; Haghighirad, A.-A. 1; Merz, M. 1,2; Bosak, A.; Le Tacon, M. ORCID iD icon 1
1 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT)
2 Karlsruhe Nano Micro Facility (KNMF), Karlsruher Institut für Technologie (KIT)

Abstract:

We use diffuse and inelastic x-ray scattering to study the formation of an incommensurate charge-density-wave (I-CDW) in BaNi$_2$As$_2$, a candidate system for charge-driven electronic nematicity. Intense diffuse scattering is observed around the modulation vector of the I-CDW, Q$_{I-CDW}$. It is already visible at room temperature and collapses into superstructure reflections in the long-range ordered state where a small orthorhombic distortion occurs. A clear dip in the dispersion of a low-energy transverse optical phonon mode is observed around Q$_{I-CDW}$. The phonon continuously softens upon cooling, ultimately driving the transition to the I-CDW state. The transverse character of the soft-phonon branch elucidates the complex pattern of the I-CDW satellites observed in the current and earlier studies and settles the debated unidirectional nature of the I-CDW. The phonon instability and its reciprocal space position are well captured by our ab initio calculations. These, however, indicate that neither Fermi surface nesting, nor enhanced momentum-dependent electron-phonon coupling can account for the I-CDW formation, demonstrating its unconventional nature.


Verlagsausgabe §
DOI: 10.5445/IR/1000153705
Veröffentlicht am 08.09.2023
Originalveröffentlichung
DOI: 10.1103/PhysRevLett.129.247602
Scopus
Zitationen: 10
Web of Science
Zitationen: 6
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Zitationen: 13
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für QuantenMaterialien und Technologien (IQMT)
Karlsruhe Nano Micro Facility (KNMF)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 12.2022
Sprache Englisch
Identifikator ISSN: 0031-9007, 1079-7114
KITopen-ID: 1000153705
HGF-Programm 47.11.02 (POF IV, LK 01) Emergent Quantum Phenomena
Erschienen in Physical Review Letters
Verlag American Physical Society (APS)
Band 129
Heft 24
Seiten Article no: 247602
Vorab online veröffentlicht am 09.12.2022
Nachgewiesen in Web of Science
Scopus
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