Related papers: Bound states in d-density-wave phases
Gapless superconductivity can arise when pairing occurs between fermion species with different Fermi surface sizes, provided there is a sufficiently large mismatch between Fermi surfaces and/or at sufficiently large coupling constant. In…
We study several models of $d$-dimensional fermions ($d=1,2,3$) with an emphasis on the properties of their gapless (metallic) phase. It occurs at $T = 0$ as a continuous transition when zeros of the partition function reach the real range…
Theoretical results for the ab-plane tunneling conductance in the d-wave model for high Tc superconductors are presented. The d-wave model predicts surface bound states below the maximum gap. A sub-dominant order parameter, stabilized by…
Topological superconductors as characterized by Majorana surface states has been actively searched for their significance in fundamental science and technological implication. The large spin-orbit coupling in Bi-Pd binaries has stimulated…
Recent work has used a U(1) gauge theory to describe the physics of Fermi pockets in the presence of fluctuating spin density wave order. We generalize this theory to an arbitrary band structure and ordering wavevector. The transition to…
We study a new class of topological charge density wave states exhibiting monopole harmonic symmetries. The density-wave ordering is equivalent to pairing in the particle-hole channel due to Fermi surface nesting under interactions. When…
A leading contender for the pairing symmetry in the Fe-pnictide high temperature superconductors is extended s-wave $s_\pm$, a nodeless state in which the pairing changes sign between Fermi surfaces. Verifying such a pairing symmetry…
Recent quantum oscillation measurements in high temperature superconductors in high magnetic fields and low temperatures have ushered in a new era. These experiments explore the normal state from which superconductivity arises and provide…
Recently a novel surface pair-density-wave (PDW) superconducting state has been discovered in Refs. [Phys. Rev. Lett. \textbf{122}, 165302 (2019)] and Phys. Rev. B \textbf{101}, 054506 (2020)], which may go through a distinct multiple phase…
We study the two-dimensional Kondo lattice model with an additional Heisenberg exchange between localized spins. In a first step we use mean-field theory with two order parameters. The first order parameter is a complex pairing amplitude…
In the theoretical analyses of impurity effects in superconductors the assumption is usually made that all quantities, except for the Green functions, are slowly varying functions of energy. When this so-called Fermi Surface Restricted…
Based on the quasiclassical theory, we investigate the vortex state in a two-band superconductor with a small gap on a three dimensional Fermi surface and a large gap on a quasi-two dimensional one, as in MgB_2. The field dependence of…
Spin-wave excitations of quarter-filled spin-density-wave state, which coexists with charge ordering, have been studied for one-dimensional extended Hubbard model with the nearest-neighbor repulsive interaction (V) and next-nearest-neighbor…
The Fermi surface as a contour of the gapless quasiparticle excitation in momentum space is studied based on a mean-field theory of the doped Mott insulator, where the underlying pseudogap phase is characterized by a two-component…
Excited-state self-energy effects in the electronic structure of Cu, a prototype weakly correlated system containing states with different degrees of localization, are investigated with emphasis on the unoccupied states up to 40 eV above…
The phase diagram of the unconstrained $t-J$ model is calculated using the random phase approximation. It is found that the extended $s$ and the $d_{x^2-y^2}$-channels are {\em not} degenerate near half filling. Extended $s$-pairing with a…
We investigate the interplay between charge density wave (CDW) order and topological nodal-line states in square-net materials. Our Ginzburg-Landau theory predicts a CDW instability that generically opens a gap at the Fermi energy while…
We investigate unconventional superconductivity in three-dimensional electronic systems with the chemical potential close to a quadratic band touching point in the band dispersion. Short-range interactions can lead to d-wave…
The anomalous proximity effect between a d-wave superconductor and a surface layer with small electronic mean free path is studied theoretically in the framework of the Eilenberger equations. The angular and spatial structure of the pair…
The two-dimensional d-wave superconducting state of the high temperature superconductors has a number of different elementary excitations: the spin-singlet Cooper pairs, the spin S=1/2 fermionic quasiparticles, and a bosonic S=1 resonant…