Temperature dependence ofH c2 and? 1 in strong coupling superconductors

Calorimetric Evidence for a Fulde-Ferrell-Larkin-Ovchinnikov Superconducting State in the Layered Organic Superconductorκ−(BEDT−TTF)2Cu(Lortz1, Wang2, Demuer3 et al. 2007Phys. Rev. Lett.273232423View full textAdd to dashboardCite

“…As the magnetic susceptibility in the normal state is not significantly renormalized compared to the expected value for free quasiparticles, we neglect Landau's spin-dependent interaction parameter ment we have to account for corrections due to the strong electron-phonon coupling. Considering the rather small ratio k B T c =@h!i ' 0:08 [29] we anticipate neither pronounced anomalies in the variation with T of the enhancement factors nor significant differences in critical-field renormalizations corresponding to first and second-order transitions, respectively [30]. As we are mainly interested in the low-T behavior we implicitly account for strongcoupling corrections by rescaling the weak-coupling results with the enhancement factor for the low-T energy gap 0 =1:76k B T c ' 1:35 [23].…”

Functional derivatives of T$\mathsf{_c}$ for a two-band superconductor: application to MgB$\mathsf{_{2}}$

“…The function δT c /δα 2 F (Ω) provides answer to the question -How are the phonons of frequency Ω effective in contributing to T c ? From the practical point of view the functional derivative δT c /δα 2 F (Ω) gives the change ∆T c in transition temperature when α 2 F (Ω) is changed by a small amount ∆α 2 F (Ω) (say, by applying pressure [3], by alloying [4,5], or by implanting small concentrations of hydrogen into a metal [6])…”

“…The concept of functional derivative δ/δα 2 F (Ω) was extended by Rainer and Bergmann [4] and others to several thermodynamic properties of isotropic superconductors (for a review and an extensive list of references see [7]). …”

Lower critical field and magnetization of strong-coupling, type II superconductors in the dirty limit

“…* The Eliashberg spectral functions used in this work are those of ref. 25. In the figure, comparison is made with the corresponding flux-line profiles in the weak-coupling limit.…”

“…This is in agreement with the early theoretical observation that strong-coupling effects are larger at higher reduced temperatures. 25 Strong-coupling effects are properly discussed in terms of the enhancement parameters of the critical fields. In Fig.…”