Local modulations of the spin-fluctuation-mediated pairing interaction by impurities ind-wave superconductors

Abstract

We present a self-consistent real space formulation of spin-fluctuation mediated d-wave pairing. By calculating all relevant inhomogeneous spin and charge susceptibilities in real space within the random phase approximation (RPA), we obtain the effective pairing interaction and study its spatial dependence near both local potential and hopping impurities. A remarkably large enhancement of the pairing interaction may be obtained near the impurity site. We discuss the relevance of our result to inhomogeneities observed by scanning tunneling spectroscopy on the surface of cuprate superconductors.

Enhancement of superconducting transition temperature by pointlike disorder and anisotropic energy gap in FeSe single crystals

“…that it enhances the pair interaction locally, as discussed in several microscopic models [73][74][75][76]. Here the basic idea is that the electronic structure is modulated locally so that it enhances the magnetic exchange in the strong coupling limit, or drives the system closer to a local Stoner instability, in the weak coupling case.…”

Impurity-induced subgap bound states in alkali-doped iron chalcogenide superconductors

“…[31][32][33][34][35][36][37][38][39][40][41][42][43] Impurity-induced magnetism is found to be absent for swave superconductors in agreement with the fact that they do not support sub-gap bound states and hence cannot produce the large DOS enhancement required for locally crossing the Stoner instability. We have calculated the local induced moments and associated LDOS for a d-wave superconductor shown in Fig.…”

“…This mechanism can be understood as a local Stoner instability and has been discussed extensively in the literature. [31][32][33][34][35][36][37][38][39][40][41][42][43] The existence of impurity-induced order may be particularly relevant to alkali doped iron chalcogenides due to the evidence of significant electronic interactions 44 and the likely presence disordered vacancies (which in the vacancy ordered state induce the BAFM order) in the superconducting regions. We note that the presence of impurity-induced magnetic order is only relevant for d-wave pairing, and hence our conclusion of absence (presence) of sub-gap bound states for d-wave (s-wave) pairing symmetry remains robust.…”

Determinant quantum Monte Carlo study of the enhancement ofd-wave pairing by charge inhomogeneity

“…It would be interesting also to explore the possible enhancement of pairing at these temperature scales by other types of charge inhomogeneities such as checkerboard patterns 67 and in the presence of nonmagnetic disorder. 68,69 …”