Evidence of s-wave superconductivity in the noncentrosymmetric La7Ir3.
Sci Rep
; 8(1): 651, 2018 01 12.
Article
en En
| MEDLINE
| ID: mdl-29330440
ABSTRACT
Superconductivity in noncentrosymmetric compounds has attracted sustained interest in the last decades. Here we present a detailed study on the transport, thermodynamic properties and the band structure of the noncentrosymmetric superconductor La 7 Ir 3 (T c ~ 2.3 K) that was recently proposed to break the time-reversal symmetry. It is found that La7Ir3 displays a moderately large electronic heat capacity (Sommerfeld coefficient γ n ~ 53.1 mJ/mol K2) and a significantly enhanced Kadowaki-Woods ratio (KWR ~32 µΩ cm mol2 K2 J-2) that is greater than the typical value (~10 µΩ cm mol2 K2 J-2) for strongly correlated electron systems. The upper critical field Hc2 was seen to be nicely described by the single-band Werthamer-Helfand-Hohenberg model down to very low temperatures. The hydrostatic pressure effects on the superconductivity were also investigated. The heat capacity below T c reveals a dominant s-wave gap with the magnitude close to the BCS value. The first-principles calculations yield the electron-phonon coupling constant λ = 0.81 and the logarithmically averaged frequency ω ln = 78.5 K, resulting in a theoretical T c = 2.5 K, close to the experimental value. Our calculations suggest that the enhanced electronic heat capacity is more likely due to electron-phonon coupling, rather than the electron-electron correlation effects. Collectively, these results place severe constraints on any theory of exotic superconductivity in this system.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Sci Rep
Año:
2018
Tipo del documento:
Article
País de afiliación:
China