Identification of specific phonon contributions in BCS-type superconductivity of boride-carbide crystals with a layer-like structure. (March 2015)

• Record Type: Journal Article
• Authors: Uzunok, H.Y.; Tütüncü, H.M.; Özer, S.; Ugˇur, Ş.; Srivastava, G.P.
• Is Part Of: Solid state communications. Volume 206(2015)
• Page Start: 1
• Page End: 5
• Publication Date: 2015-03
• Subjects: A. Dicarbides -- D. Superconductivity -- D. Electronic structure -- D. Phonons; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2015.01.010
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: We report on an ab initio study of the BCS-type superconductivity in the intermetallic borocarbides YPd2 B2 C, YPt2 B2 C and LaPt2 B2 C with a layer-like structure. The largest contribution to the electron-phonon coupling constant λ is identified to come from transverse acoustic phonons at a zone-edge, arising from the atomic vibrations in the boron-transition metal layer. A detailed examination of the atomic geometry in the boron-transition metal layer, the electron-phonon coupling constant λ, and the logarithmically averaged phonon frequency ω ln helps explain the relatively higher superconducting temperature T c of YPd2 B2 C (20.6 K) compared to that of YPt2 B2 C (11.3 K) and LaPt2 B2C (10.40 K). Abstract : Highlights: The electronic structures of YPd2 B2 C, YPt2 B2 C and LaPt2 B2 C are studied using ab initio pseudopotential method. Phonons are studied using a linear response theory. The lowest phonon mode couples more strongly with electrons. The calculated T C of 20.6 K for YPd2 B2 C is in agreement with the experimental value of 21 K.