Lattice dynamics in the FeSi-based family of superconductors

• Published in: Europhysics letters Vol. 146; no. 4; pp. 46002 - 46007
• Main Authors: Layek, S., Hansen, M. F., Vaney, J.-B., Toulemonde, P., Tencé, S., Boullay, P., Cano, A., Méasson, M.-A.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences, IOP Publishing and Società Italiana di Fisica 01-05-2024; IOP Publishing; European Physical Society / EDP Sciences / Società Italiana di Fisica / IOP Publishing
• Subjects: Couplings; Dynamic structural analysis; Electron diffraction; First principles; Group 5A compounds; Iron silicide; Lattice vibration; Physics; Raman spectroscopy; Superconductors; Strongly Correlated Electrons (cond-mat.str-el); Superconductivity (cond-mat.supr-con); FOS: Physical sciences
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/0295-5075/ad3b37

Abstract
The lattice dynamics of the superconducting materials LaFeSiH and LaFeSiO
1-
δ
as well as their intermetallic precursor LaFeSi are investigated by polarized Raman spectroscopy and first-principles calculations, together with X-ray and advanced electron diffraction techniques for their structural analysis. We find that the Fe-dominated Raman-active modes reflect the chemical peculiarities of these silicides compared to their pnictide counterparts, with enhanced structural couplings between the FeSi layer and the spacer that can be related to the ionic
vs
. covalent character of the latter. In addition, we find signatures of enhanced electron-phonon coupling for some of the Raman-active modes. Beyond that, our study reveals intriguing Fe-based Raman features as well as structural subtleties in LaFeSiH suggesting that this superconductor may formally be non-centrosymmetric.