Related papers: Two pairing parameters in superconducting grains
Scanning tunneling spectroscopy studies on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ suggest the presence of electronic inhomogeneity with a large spatial variation in gap size. Andersen {\it et al} have modelled this variation by assuming a…
The two-dimensional Hubbard model is studied for small values of the interaction strength (U of the order of the hopping amplitude t), using a variational ansatz well suited for this regime. The wave function, a refined Gutzwiller ansatz,…
The subbands of weakly coupled double-layer two dimensional electron gas systems consist of narrowly spaced pairs whose corresponding wavefunctions are symmetric and antisymmetric combinations of isolated layer subband wavefunctions. The…
We succeeded in the synthesis of high-Jc MgB2 bulks via high energy ball-milling of elemental Mg and B powder at ambient temperatures. Alternatively to longtime mechanical alloying technique, the mixed powder was ball-milled for only 1h and…
A simple model of cuprate superconductivity with an electron spectrum prepared by doping is developed. The pair-transfer interaction couples the itinerant band with two components ("hot'' and "cold'') of the defect subsystem. There are…
The magnetoresistance of a granular superconductor in a strong magnetic field is considered. It is assumed that this field destroys the superconducting gap in each grain, such that all interesting effects considered in the paper are due to…
The properties of a balanced two-component Fermi gas in a one-dimensional harmonic trap are studied by means of the coupled cluster method. For few fermions we recover the results of exact diagonalization, yet with this method we are able…
We study the effect of the chemical potential on the results of the BCS theory of superconductivity. We assume that the pairing interaction is manifested between electrons of single-particle energies in an interval $[\mu - \hbar\omega_c,…
We discuss the class of superconductors which have pairing correlations which are odd in frequency, as introduced originally by Berezinskii and more recently by Balatsky and Abrahams. As follows from the equations of motion, a natural…
We study finite size effects in superconducting metallic grains and determine the BCS order parameter and the low energy excitation spectrum in terms of size, and shape of the grain. Our approach combines the BCS self-consistency condition,…
beta-Bi2Pd compound has been proposed as another example of a multi-gap superconductor [Y. Imai et al., J. Phys. Soc. Jap. 81, 113708 (2012)]. Here, we report on measurements of several important physical quantities capable to show a…
It is shown that a two-component percolation model can explain an experimentally observed behavior, namely that a network built up by a mixture of sintered nanocrystalline semiconducting n- and p-grains can exhibit selective behavior, i.e.…
Starting from the Ginzburg-Landau energy functional, we discuss how the presence of two order parameters and the coupling between them influence a superconducting ring in the fluctuative regime. Our method is exact, but requires numerical…
The amplitude of ground state superconducting energy gap $\Delta(0)$ and relative jump in electronic specific heat at the transition temperature, $\Delta$$C$${/}$$\gamma$$T_c$, are primary fundamental parameters of any superconductor. There…
We describe strongly attractive carriers in cuprates in the framework of a simple quasi-one dimensional Hamiltonian with a local attraction. In contrast with the conventional BCS theory there are two energy scales, a temperature independent…
In granular superconductors, individual grains can contain bound Cooper pairs while the system as a whole is strongly insulating. In such cases the conductivity is determined by electron hopping between localized states in individual…
We introduce and study a simple unbalanced holographic superconductor model with two scalar order parameters. The attention is focused on the possibility of coexisting orderings corresponding to the concomitant condensation of two scalar…
A combination of strong Cooper pairing and weak superconducting fluctuations is crucial to achieve and stabilize high-Tc superconductivity. We demonstrate that a coexistence of a shallow carrier band with strong pairing and a deep band with…
We investigate transport in a granular metallic system at large tunneling conductance between the grains, $g_T\gg 1$. We show that at low temperatures, $T\leq g_T\delta $, where $\delta$ is the single mean energy level spacing in a grain,…
The remarkable universality of the cuprate $T_c$ dome suggests a very fundamental unifying principle. Moreover, the superconducting gap is known to persist above $T_c$ in the pseudogap phase of all cuprates. So, contrary to BCS, the gap…