Q-dependent electron-phonon coupling induced phonon softening and non-conventional critical behavior in the CDW superconductor LaPt 2 Si 2

Nocerino, E.Alba Nova Universitetscentrum,AlbaNova University Center. Stockholm Center for Physics, Astronomy and Biotechnology (author)

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.

Stuhr, U. (author)
San Lorenzo, I.Niels Bohr Institute,Politecnico di Torino,Polytechnic University of Turin (author)
Mazza, F.Technische Universität Wien,Vienna University of Technology (author)
Mazzone, Daniel G. (author)
Hellsvik, JohanKungliga Tekniska Högskolan (KTH),Royal Institute of Technology (KTH) (author)
Hasegawa, S.University of Tokyo, Japan (author)
Asai, S.University of Tokyo, Japan (author)
Masuda, T.University of Tokyo, Japan,High Energy Accelerator Research Organization (KEK) (author)
Itoh, S.High Energy Accelerator Research Organization (KEK) (author)
Minelli, A.University Of Oxford (author)
Hossain, ZakirIndian Institute of Technology (author)
Thamizhavel, A.Tata Institute of Fundamental Research (author)
Lefmann, K.Niels Bohr Institute (author)
Sassa, Yasmine,1981Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)sassa (author)
Månsson, MartinAlba Nova Universitetscentrum,AlbaNova University Center. Stockholm Center for Physics, Astronomy and Biotechnology (author)
Alba Nova UniversitetscentrumNiels Bohr Institute (creator_code:org_t)

By the author/editor: Nocerino, E.; Stuhr, U.; San Lorenzo, I.; Mazza, F.; Mazzone, Daniel ...; Hellsvik, Johan; show more...; Hasegawa, S.; Asai, S.; Masuda, T.; Itoh, S.; Minelli, A.; Hossain, Zakir; Thamizhavel, A.; Lefmann, K.; Sassa, Yasmine, ...; Månsson, Martin; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Condensed Matter ...

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