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

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Documents

  • 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
  • Lefmann, Kim
  • Y. Sassa
  • M. Månsson

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.

Original languageEnglish
Article number100621
JournalJournal of Science: Advanced Materials and Devices
Volume8
Issue number4
Number of pages10
ISSN2468-2284
DOIs
Publication statusPublished - 2023

Bibliographical note

Funding Information:
The TAS-INS measurements were performed at the Swiss Spallation Neutron Source (SINQ), at the EIGER spectrometer at the Paul Scherrer Institute in Villigen, Switzerland (beamtimes proposals: 20211069 and 20212576). The TOF-INS measurements were performed at the Materials and Life Science Experimental Facility (MLF), at the HRC spectrometer at the Japan Proton Accelerator Research Complex in Tokai, Japan (beamtime proposal: 2019B0421). The authors wish to thank the staff of PSI and J-PARC for the valuable help in the neutron spectroscopy experiments. The authors also wish to thank Dr J. Lass and Prof Dr C. Niedermayer for the fruitful discussions and support during the EIGER experiments. This research is funded by the Swedish Foundation for Strategic Research ( SSF ) within the Swedish national graduate school in neutron scattering (SwedNess). T.M. was supported by JSPS KAKENHI Grants No. JP21H04441. A.M. would like to acknowledge financial support from the E.R.C . (Grant 788144 ). Y.S. acknowledges funding from the Swedish Research Council (VR) through a Starting Grant (Dnr. 2017-05078) and Area of Advances-Material Sciences from Chalmers University of Technology. Y.S. is also supported by Wallenberg Young Fellow through the grant KAW 2021.0150.

Funding Information:
The TAS-INS measurements were performed at the Swiss Spallation Neutron Source (SINQ), at the EIGER spectrometer at the Paul Scherrer Institute in Villigen, Switzerland (beamtimes proposals: 20211069 and 20212576). The TOF-INS measurements were performed at the Materials and Life Science Experimental Facility (MLF), at the HRC spectrometer at the Japan Proton Accelerator Research Complex in Tokai, Japan (beamtime proposal: 2019B0421). The authors wish to thank the staff of PSI and J-PARC for the valuable help in the neutron spectroscopy experiments. The authors also wish to thank Dr J. Lass and Prof Dr C. Niedermayer for the fruitful discussions and support during the EIGER experiments. This research is funded by the Swedish Foundation for Strategic Research (SSF) within the Swedish national graduate school in neutron scattering (SwedNess). T.M. was supported by JSPS KAKENHI Grants No. JP21H04441. A.M. would like to acknowledge financial support from the E.R.C. (Grant 788144). Y.S. acknowledges funding from the Swedish Research Council (VR) through a Starting Grant (Dnr. 2017-05078) and Area of Advances-Material Sciences from Chalmers University of Technology. Y.S. is also supported by Wallenberg Young Fellow through the grant KAW 2021.0150.

Publisher Copyright:
© 2023 Vietnam National University, Hanoi

    Research areas

  • CDW discommensuration, Charge density wave, Inelastic neutron scattering, Phonon softening, Unconventional superconductivity

ID: 381846567