Q-dependent electron-phonon coupling induced phonon softening and non-conventional critical behavior in the CDW superconductor LaPt2 Si2
Journal article, 2023
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.
CDW discommensuration
Phonon softening
Unconventional superconductivity
Charge density wave
Inelastic neutron scattering
Author
E. Nocerino
AlbaNova University Center
U. Stuhr
Laboratory for Neutron Scattering, Villigen
I. San Lorenzo
Niels Bohr Institute
Polytechnic University of Turin
F. Mazza
Vienna University of Technology
Daniel G. Mazzone
Laboratory for Neutron Scattering, Villigen
Johan Hellsvik
Royal Institute of Technology (KTH)
S. Hasegawa
University of Tokyo
S. Asai
University of Tokyo
T. Masuda
High Energy Accelerator Research Organization
University of Tokyo
S. Itoh
High Energy Accelerator Research Organization
A. Minelli
University of Oxford
Zakir Hossain
Indian Institute of Technology
A. Thamizhavel
Tata Institute of Fundamental Research
K. Lefmann
Niels Bohr Institute
Yasmine Sassa
Chalmers, Physics, Materials Physics
Martin Månsson
AlbaNova University Center
Journal of Science: Advanced Materials and Devices
24682284 (ISSN) 24682179 (eISSN)
Vol. 8 4 100621Realization of Novel Low‐Dimensional Skyrmion Systems
Swedish Research Council (VR) (2017-05078), 2019-06-01 -- 2021-12-31.
Subject Categories
Condensed Matter Physics
DOI
10.1016/j.jsamd.2023.100621