Structural phases of elemental Ga: Universal relations in conventional superconductors

Abstract

The temperature dependent measurements of the thermodynamic critical field and the specific heat for the pressure stabilized Ga-II phase of elemental Gallium are presented. The discussion of these and other Ga phases data in the context of elemental and binary phonon-mediated type-I superconductors allowed to establish simple scaling relations between BCS quantities such as Bc(0)/Tc √ γe and the specific heat jump at Tc versus the coupling strength 2∆/kBTc [∆ and Bc(0) are the zerotemperature values of the superconducting energy gap and the thermodynamic critical field, respectively, Tc is the transition temperature, and γe is the electronic specific heat]. The scaling relations can be analytically expressed by taking into account strong-coupling corrections to BCS theory. Such correlations can naturally explain the linear relation between Bc(0) and Tc, which holds for type-I superconducting materials.

Single-gap versus two-gap scenario: Specific heat and thermodynamic critical field of the noncentrosymmetric superconductor BeAu

“…For example, this is the case in the analysis of conventional elemental and binary superconductors within the framework of the empirical α model (see Refs. [34][35][36][37][38]) and the Eliashberg approach (see the classic reviews of Carbotte [39] and Marsiglio and Carbotte [40]) and the two-gap superconductors within the self-consistent approach using models developed by Kogan et al [41,42] and Bussmann-Holder et al [43][44][45].…”

Three-wall piston-cylinder type pressure cell for muon-spin rotation/relaxation experiments

“…The experimental data were analyzed by separating the TF-µSR response of the sample and the background contributions by following the procedure described in Refs. [29][30][31][32][33]. The magnetic field distribution in a type-I superconductor, as elemental Indium, in the intermediate state, consists of two sharp peaks corresponding to the response of the domains remaining in the Meissner state (B ≡ 0) and in the normal state (B ≡ B c > B ex , B c is the thermodynamic critical field), see Fig.…”

Isotropic single gap superconductivity of elemental Pb: the `smiling' approach

“…The transverse-field muon-spin rotation/relaxation (TF-µSR) experiments were conducted using the Dolly spectrometer (πE1 beam line) at the Paul Scherrer Institute, Switzerland. Measurements were performed in the intermediate state of superconducting Pb, i.e., when the sample volume is separated into the normal state and the superconducting state (Meissner) domains [15,18,22,[26][27][28][29][30][31][32]. Two sets of experiments were performed.…”