Related papers: Generalized Anderson's theorem for superconductors…
The pseudogap phenomena in the cuprate superconductors requires a theory beyond the mean field BCS level. A natural candidate is to include strong pairing fluctuations, and treat the two-particle and single particle Green's functions…
We apply the Coherent Potential Approximation (CPA) to a simple extended Hubbard model with a nearest and next nearest neighbour hopping for disordered superconductors with s-, d- and p-wave pairing. We show how the Van Hove singularities…
We introduce a new $\Phi $-derivable approach for the Anderson impurity model in a BCS superconductor. The regime of validity of this conserving theory extends well beyond that of the Hartree-Fock approximation. This is the first…
In a flat band superconductor, bosonic excitations can disperse while unpaired electrons are immobile. To study this strongly interacting system, we construct a family of multi-band Hubbard models with exact eta-pairing ground states in all…
We report on a study of electric resistivity and magnetic susceptibility measurements in electron irradiated SrTi$_{0.987}$Nb$_{0.013}$O$_3$ single crystals. Point-like defects, induced by electron irradiation, lead to an almost threefold…
Superconductivity forms out of the condensation of Cooper pairs of electrons. The mechanism by which Cooper pairs are created in non-conventional superconductors is often elusive because experimental signatures that connect a specific…
Topological superconductors have been theoretically predicted as a new class of time-reversal-invariant superconductors which are fully gapped in the bulk but have protected gapless surface Andreev bound states. In this work, we provide a…
It is analyzed what fundamental new information for the properties of the superconductors can be obtained by systematic investigation of the Bernoulli effect. It is shown that it is a tool to determine the effective mass of Cooper pairs,…
Superconductors derived from topological insulators and topological crystalline insulators by doping have long been considered to be candidates as topological superconductors. Pb$_{0.5}$Sn$_{0.5}$Te is a topological crystalline insulator…
Generalization of a disordered metal's theory has been proposed when scattering of quasiparticles by impurities is caused with a retarded interaction. It was shown that in this case Anderson's theorem was violated in the sense that…
We show the emergence of a new class of superconductivity in multiorbital systems, focusing on non-Kramers f$^2$ states. The Cooper pairs in this class of superconductivity mainly consist of local pairs with the same symmetry as the local…
Topological superconductors represent a newly predicted phase of matter that is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of their topological character, topological…
Most superconducting materials exhibit a vanishing density of states at the Fermi level and Anderson's theorem posits that the superconducting gap is robust against nonmagnetic disorder. Although dilute magnetic impurities lead to localized…
How the superconductivity in unconventional superconductors emerges from the diverse mother normal states is still a big puzzle. Whatever the mother normal states are the superconductivity is {\em normal} with BCS-like behaviours of the…
We present a theory of ferromagnetic superconductivity that emerges upon doping a correlated ferromagnetic insulator through the condensation of excitonic Cooper pairs, which are charge-$2e$ bosonic quasiparticles made of Cooper pairs…
We consider an Anderson impurity (A) weakly connected to a superconducting electrode (S) on one side and a superconducting or a normal metal electrode (N) on the other side. A general path integral formalism is developed and the response of…
Based on the five-orbital model, we study the effect of local impurity in iron pnictides, and find that the interband impurity scattering is promoted by the d-orbital degree of freedom. This fact means that the fully-gapped sign-reversing…
A translation-invariant (TI) bipolaron theory of superconductivity based, like Bardeen-Cooper-Schrieffer theory, on Fr\"ohlich Hamiltonian is presented. Here the role of Cooper pairs belongs to TI bipolarons which are pairs of spatially…
We report the first-principles study of superconducting critical temperature and superconducting properties of Fe-based superconductors taking into account on the same footing phonon, charge and spin-fluctuation mediated Cooper pairing. We…
The two-channel Anderson lattice model which has $SU(2)\otimes SU(2)$ symmetry is of relevance to understanding of the magnetic, quadrupolar and superconducting phases in U$_{1-x}$Th$_x$Be$_{13}$ or Pr base skutterudite compounds such as…