Approximating the electron-phonon coupling constant in superconductors from thermodynamic data

SrAuSi3: A Noncentrosymmetric Superconductor

“…Substituting these values into the equation, we obtain an electron–phonon coupling constant (λ ep ) of 0.97 for SrAuSi 3 . This λ ep value is close to that for a niobium metal (0.82) appropriate for a moderately strong-coupling superconductor. − , A generalized relationship between the electron–phonon coupling constant (λ ep ) and the normalized specific heat jump [Δ C el /(γ n T C )] for weak- to strong-coupling superconductors has been reported by Dalrymple et al The results [λ ep = 0.97, and Δ C el /(γ n T C ) = 1.92] for SrAuSi 3 satisfy the Dalrymple model.…”

“…This λ ep value is close to that for a niobium metal (0.82) appropriate for a moderately strong-coupling superconductor. [70][71][72]76 A generalized relationship between the electron−phonon coupling constant (λ ep ) and the normalized specific heat jump [ΔC el /(γ n T C )] for weak-to strong-coupling superconductors has been reported by Dalrymple et al 77 The 76 Using the standard value of 0.13 for μ* 78 and the obtained values of λ ep (0.97) and Θ D (410 K), we obtain an ideal T C of ∼19 K for SrAuSi 3 . However, this result conflicts with the experimental result that the actual T C is 1.54 K. The observed T C is too low for a conventional superconductor with such a high Debye temperature (Θ D ∼ 410 K) and strong electron−phonon coupling (λ ep ∼ 0.97).…”

Physical properties of superconducting Ca10(Pt4As8)((Fe0.92Pt0.08)2As2)5 crystal and comprehensive cognition on the transition temperature for Ca10-3(4)-8

“…shown below. The fact that λ ep could be set to zero illustrates unlike the traditional superconductors which mainly depend on the help of strong interactions between electrons and phonons to form Cooper pairs, for example λ ep =1.6 3 for Hg and λ ep =1.8 35 for Nb 3 Sn [34], the electron-phonon coupling is relatively weak in the Fe based superconductors. From the value of β, the Debye temperature Θ D of the crystal can be evaluated using the expression [33],…”