Phase dependent differential thermopower of s-wave-superconductor–normal-metal–d-wave-superconductor junctions: Pair-breaking effects and Gaussian fluctuations

Abstract

We start with revisiting our previous results on thermoelectric response of s-wave-superconductor–normal-metal–s-wave-superconductor (SNS) configuration in a C-shaped BixPb1−xSr2CaCu2Oy sample in order to include strong fluctuation effects. Then, by appropriate generalization of the Ginzburg-Landau theory based on admixture of s-wave (S) and d-wave (D) superconductors, we consider a differential thermoelectric power (TEP) of s-wave-superconductor–normal-metal–d-wave-superconductor (SND) junction. In addition to its strong dependence on the relative phase θ=φs−φd between the two superconductors, two major effects are shown to influence the behavior of the predicted TEP. One, based on the chemical imbalance at SD interface, results in a pronounced maximum of the TEP peak near θ=π/2 (where the so-called s+id mixed pairing state is formed) for two identical superconductors with Tcd=Tcs≡Tc. Another effect, which should manifest itself at SD interface comprising an s-wave low-Tc superconductor and a d-wave high-Tc superconductor with Tcd≠Tcs, predicts Sp∝Tcd−Tcs for the TEP peak value. The experimental conditions under which the predicted behavior of the induced differential TEP can be measured are discussed.

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