Q-dependent electron-phonon coupling induced phonon softening and non-conventional critical behavior in the CDW superconductor LaPt2Si2

E. Nocerino; U. Stuhr; I. San Lorenzo; F. Mazza; D.G. Mazzone; J. Hellsvik; S. Hasegawa; S. Asai; T. Masuda; S. Itoh; A. Minelli; Z. Hossain; A. Thamizhavel; K. Lefmann; Y. Sassa; M. Månsson

Journal of Science: Advanced Materials and Devices (Dec 2023)

Q-dependent electron-phonon coupling induced phonon softening and non-conventional critical behavior in the CDW superconductor LaPt2Si2

E. Nocerino,
U. Stuhr,
I. San Lorenzo,
F. Mazza,
D.G. Mazzone,
J. Hellsvik,
S. Hasegawa,
S. Asai,
T. Masuda,
S. Itoh,
A. Minelli,
Z. Hossain,
A. Thamizhavel,
K. Lefmann,
Y. Sassa,
M. Månsson

Affiliations

E. Nocerino: KTH Royal Institute of Technology, Department of Applied Physics, Alba Nova University Center, Stockholm, SE-114 21, Sweden; Corresponding author.
U. Stuhr: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland
I. San Lorenzo: Nanoscience Center, Niels Bohr Institute, University of Copenhagen, Nørre Allé 59, DK-2100, Copenhagen O, Denmark; Department of Applied Science and Technology, Politecnico di Torino, Corso Duca Degli Abruzzi 24 10129, Torino, Italy
F. Mazza: Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstraße 8–10, 1040, Vienna, Austria
D.G. Mazzone: Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland
J. Hellsvik: PDC Center for High Performance Computing, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden; Nordita, KTH Royal Institute of Technology and Stockholm University, Hannes Alfvéns väg 12, SE-106 91, Stockholm, Sweden
S. Hasegawa: Neutron Science Laboratory, Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
S. Asai: Neutron Science Laboratory, Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
T. Masuda: Neutron Science Laboratory, Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan; Trans-scale Quantum Science Institute, The University of Tokyo, Tokyo 113-0033, Japan; Institute of Materials Structure Science, High Energy Accelerator Research Organization, Ibaraki 305-0801, Japan
S. Itoh: Institute of Materials Structure Science, High Energy Accelerator Research Organization, Ibaraki 305-0801, Japan
A. Minelli: Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, United Kingdom
Z. Hossain: Department of Physics, Indian Institute of Technology, Kanpur 208016, India
A. Thamizhavel: DCMPMS, Tata Institute of Fundamental Research, Mumbai 400005, India
K. Lefmann: Nanoscience Center, Niels Bohr Institute, University of Copenhagen, Nørre Allé 59, DK-2100, Copenhagen O, Denmark
Y. Sassa: Department of Physics, Chalmers University of Technology, SE-412, Göteborg, Sweden
M. Månsson: KTH Royal Institute of Technology, Department of Applied Physics, Alba Nova University Center, Stockholm, SE-114 21, Sweden; Corresponding author.

Journal volume & issue: Vol. 8, no. 4
p. 100621

Abstract

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This paper reports the first experimental observation of phonons and their softening on single crystalline LaPt2Si2 via inelastic neutron scattering. From the temperature dependence of the phonon frequency in close proximity to the charge density wave (CDW) q-vector, we obtain a CDW transition temperature of TCDW = 230 K and a critical exponent β = 0.28 ± 0.03. This value is suggestive of a non-conventional critical behavior for the CDW phase transition in LaPt2Si2, compatible with a scenario of CDW discommensuration (DC). The DC would be caused by the existence of two CDWs in this material, propagating separately in the non equivalent (Si1–Pt2–Si1) and (Pt1–Si2–Pt1) layers, respectively, with transition temperatures TCDW−1 = 230 K and TCDW−2 = 110 K. A strong q-dependence of the electron-phonon coupling has been identified as the driving mechanism for the CDW transition at TCDW−1 = 230 K while a CDW with 3-dimensional character, and Fermi surface quasi-nesting as a driving mechanism, is suggested for the transition at TCDW−2 = 110 K. Our results clarify some aspects of the CDW transition in LaPt2Si2 which have been so far misinterpreted by both theoretical predictions and experimental observations and give direct insight into its actual temperature dependence.

Published in Journal of Science: Advanced Materials and Devices

ISSN: 2468-2284 (Print); 2468-2179 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: https://www.journals.elsevier.com/journal-of-science-advanced-materials-and-devices

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