Related papers: Order parameter sign-reversal near $s_\pm$-superco…
The order parameter of High-T$_{c}$ superconductors through a series of experiments has been quite conclusively demonstrated to not be of the normal $s-wave$ type. It is either a pure $d_{x^{2}-y^{2}}$-wave type or a mixture of a…
We studied the effects of nonmagnetic impurities on high-temperature superconductors by solving the Bogoliubov-de Gennes equations on a two-dimensional lattice via exact diagonalization technique in a fully self-consistent way. We found…
The concept of the order parameter is extremely useful in physics. Here, I discuss extensions of this concept to cases when the order parameter is no longer a constant but fluctuates or oscillates in space and time. This allows one to…
Effects of disorder on electron-doped iron pnictides are investigated systematically based on self-consistent Bogoliubov-de Gennes equations. Multiply impurities with same scattering potential (SP) are randomly distributed in a square…
We consider a superconductor with surface suppression of the BCS pairing constant $\lambda(x)$. We analytically find the gap in the surface density of states (DOS), behavior of the DOS $\nu(E)$ above the gap, a "vertical" peculiarity of the…
Surface superconductivity is studied within Ginzburg-Landau theory for two classes of models for the order parameter of UPt$_{3}$. The first class assumes two independent one-dimensional order parameters ($AB$ models), while the second…
We consider different effects that arise when time-reversal symmetry breaking superconductors are subjected to an external magnetic field, thus rendering the superconductor to be in the mixed state. We focus in particular on two…
An intrinsic gap depression at the Superconductor-Insulator interface due to the very short value of the coherence length in High-Tc Superconductors [HTSs] is considered, in the framework of a mixed (s+id)-wave pair symmetry for the order…
We present an approach for determining susceptibilities and order parameters in multi-band Hubbard model within functional renormalization group method, and apply it to study various instabilities of the FeAs-based high temperature…
We study the proximity effect in good contacts between normal metals and high Tc (d-wave) superconductors. We present theoretical results for the spatially dependent order parameter and local density of states, including effects of impurity…
We analyze the local density of states (LDOS) of heterostructures consisting of alternating ferromagnet, $F$, and superconductor, $S$, layers. We consider structures of the $SFS$ and $SFSFSFS$ type, with thin nanometer scale $F$ and $S$…
We study a d-wave superconductor with dominant $d_{x^2-y^2}$-wave order parameter and subdominant pairing in either the $s$- or the $d_{xy}$-wave channel near a surface. In particular we analyze the influence of surface roughness on the…
We study inelastic (dynamical) impurity scattering effects in two-band superconductors with the same ($s_{++}$ wave) or different ($s_\pm$ wave) sign order parameters. We focus on the enhancement of the superconducting transition…
We investigate the symmetry of the superconducting order parameter in the proximity of a phase-separation or of an incommensurate charge-density-wave instability. The attractive effective interaction at small or intermediate transferred…
We consider a problem of superconductivity coexistence with the spin-density-wave order in disordered multiband metals. It is assumed that random variations of the disorder potential on short length scales render the interactions between…
In Ginzburg-Landau Theory of superconductivity, the density and location of the superconducting electrons are measured by a complex-valued wave function, the order parameter. In this paper, when the intensity of the applied magnetic field…
We derive an order-parameter field theory for a quantum phase transition between a disordered metal and an exotic (non-s-wave) superconductor. Mode coupling effects between the order parameter and other fermionic soft modes lead to an…
Most iron-based superconductors are characterized by the s+- symmetry of their order parameter, and are expected to go through a transition to the s++ state if enough disorder is introduced. We previously reported the observation of this…
Nanoscale inhomogeneity seems to be a central feature of the d-wave superconductivity in the cuprates. Such a feature can strongly affect the local density of states (LDOS) and the spectral weight functions. Within the Bogoliubov-de Gennes…
Identifying the symmetry of the superconducting order parameter in the recently-discovered ferro-oxypnictide family of superconductors, RFeAsO$_{1-x}$F$_{y}$, where $R$ is a rare earth, is a high priority. Many of the proposed order…