Q-dependent electron-phonon coupling induced phonon softening and non-conventional critical behavior in the CDW superconductor LaPt2Si2
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 100621

Realization 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

More information

Latest update

5/29/2024