Related papers: Superconductivity in repulsive electron systems ha…
We have revisited Cooper's one pair problem of calculating the binding energy for two electrons, experiencing an attractive interaction near the Fermi surface, in case of quasi one dimensional lattice system. Though it is a generalized…
Charge density wave (CDW), the periodic modulation of the electronic charge density, will open a gap on the Fermi surface that commonly leads to decreased or vanishing conductivity. On the other hand superconductivity, a commonly believed…
A bulk superconductor possessing a topological surface state at the Fermi level is a promising system to realize long-sought topological superconductivity. Although several candidate materials have been proposed, experimental demonstrations…
Stimulated by the recent finding of Na$_{0.35}$CoO$_2$.1.3H$_2$O superconductor, we investigate superconducting instabilities on a 2D triangular lattice in the repulsive Hubbard model. Using the third-order perturbation expansion with…
The origin of superconductivity in bulk SrTiO$_{3}$ is a mystery, since the non-monotonous variation of the critical transition with carrier concentration defies the expectations of the crudest version of the BCS theory. Here, employing the…
We examine the possibility of high temperature superconductivity from two-dimensional semiconductor without antiferromagnetic fluctuations. The weak coupling BCS theory is applied, especially where the Fermi level is near the bottom of the…
A precursor effect on the Fermi surface in the two-dimensional Hubbard model at finite temperatures near the antiferromagnetic instability is studied using three different itinerant approaches: the second order perturbation theory, the…
A new analytic treatment of the two-dimensional Hubbard model at finite temperature and chemical potential is presented. A next nearest neighbor hopping term of strength t' is included. This analysis is based upon a formulation of the…
A microscopic Hamiltonian reflecting the correct symmetry of $f$-orbitals is proposed to discuss superconductivity in heavy fermion systems. In the orbitally degenerate region in which not only spin fluctuations but also orbital…
In high-temperature cuprate superconductors, the anti-ferromagnetic spin fluctuations are thought to have a very important role in naturally producing an attractive interaction between the electrons in the $d$-wave channel. The connection…
The iron-pnictide superconductors have a layered structureformed by stacks of FeAs planes from which the superconductivity originates. Given the multiband and quasi three-dimensional \cite{3D_SC} (3D) electronic structure of these…
On the basis of spin and pairing fluctuation-exchange approximation, we study the superconductivity in quasi-two-dimensional Hubbard model. The integral equations for the Green's function are self-consistently solved by numerical…
We have systematically studied superconducting instabilities in the repulsive Hubbard model for d-wave and p-wave pairing in various 2D and 3D lattices. Using fluctuation exchange approximation, we consider 3D face centered cubic lattice,…
Heterostructures containing strongly correlated electron systems provide a platform to clarify interplay of electron correlation and Rashba spin-orbit coupling in unconventional superconductors. Motivated by recent fabrication of…
We study theoretically competition between the charge ordering and the superconductivity in two-dimensional organic conductor beta-(meso-DMBEDT-TTF)_2PF_6. We analyze the extended Hubbard model on a weakly-dimerized lattice based on the…
We propose an experiment-based strategy for finding new high transition temperature superconductors that is based on the well-established spin fluctuation magnetic gateway to superconductivity in which the attractive quasiparticle…
This survey provides a brief account for the start of organic superconductivity motivated by the quest for high Tc superconductors and its development since the eighties'. Besides superconductivity found in 1D organics in 1980, progresses…
We consider the possibility of formation of an unconventional spin density wave (USDW) in quasi-one dimensional electronic systems. In analogy with unconventional superconductivity, we develop a mean field theory of SDW allowing for the…
We define a `hyperconductor' to be a material whose electrical and thermal DC conductivities are infinite at zero temperature and finite at any non-zero temperature. The low-temperature behavior of a hyperconductor is controlled by a…
The pairing of two electrons on a Fermi surface due to an infinitesimal attraction between them always results in a superconducting instability at zero temperature ($T=0$). The equivalent question of pairing instability on a Luttinger…