Related papers: Superfluid density and specific heat within self-c…
Two-band superconductivity has become an important topic over the last ten years. Extensive experimental and theoretical studies started with MgB2 and are now focused on the iron-based and other new superconductors. In this review, I…
We show that a clean multiband superconductor may display one or several phase transitions with increasing temperature from or to frustrated configurations of the relative phases of the superconducting order parameters. These transitions…
We present theoretical analysis of the normal state resistivity in multiband superconductors in the framework of Eliashberg theory. The results are compared with measurements of the temperature dependence of normal state resistivity of…
Theoretical ideas and experimental results concerning high temperature superconductors are reviewed. Special emphasis is given to calculations carried out with the help of computers applied to models of strongly correlated electrons…
We characterize the superconducting state of phase pure polycrystalline samples of the new layered superconductor MgB$_2$ by specific heat measurements in magnetic fields up to 9 T. The characteristic jump at the superconducting transition…
A two-fluid model is proposed to describe the transport properties of granular superconductors. Using the resistively shunted junction model and some aspects of the two-level system theory, a statistical model is developed which takes into…
We study the effects of random nonmagnetic impurities on the superconducting transition temperature $T_c$ in a two-band superconductor, where we assume the equal-time spin-singlet s-wave pair potential in each conduction band and the…
We present the first results of directional point-contact measurements in Mg_{1-x}Mn_{x}B_2 single crystals, with x up to 0.015 and bulk T_c down to 13.3 K. The order parameters Delta_{sigma} and Delta_{pi} were obtained by fitting the…
Traditionally, the characteristic length of a superconducting condensate is associated with the spatial distribution of the corresponding gap function. However, the superconducting condensate is the quantum condensate of Cooper pairs and…
The microwave properties of polycrystalline MgB2 thin films prepared by the so-called in-situ method are investigated. The characterization of the films at microwave frequencies was obtained by a coplanar resonator technique. The analysis…
The two-band model as introduced by Suhl, Matthias and Walker [Phys. Rev. Lett. 3, 551 (1959)] accounts for multiple energy bands in the vicinity of the Fermi energy which could contribute to electron pairing in superconducting systems.…
MgB2 superconducting wires with critical temperature Tc approaching 40 K were used for preparation of MgB2/Ag and MgB2/In junctions. The differential conductance vs. voltage characteristics of N-S junctions exhibit clear contribution of…
We study the new binary intermetallic superconductor MgB2 using high-resolution photo-emission spectroscopy. The superconducting-state spectrum measured at 5.4 K shows a coherent peak with a shoulder structure, in sharp contrast to that…
Polycrystalline samples of the recently discovered MgCNi3 superconductor were investigated by transport, ac susceptibility, dc magnetization and specific heat measurements in magnetic fields up to 16 T. Consistent results were obtained for…
We present a state-of-the-art x-ray diffraction study of the charge density wave order in 1T-TaS2 as a function of temperature and pressure. Our results prove that the charge density wave, which we characterize in terms of wave vector,…
We present self-consistent calculations of the multi-gap structure measured in some Fe-based superconductors. These materials are known to have structural disorder in real space and a multi-gap structure due to the $3d$ Fe-orbitals…
Two-band electronic structures with a valence and a conduction band separated by a tunable energy gap and with pairing of electrons in different channels can be relevant to investigate the properties of two-dimensional multiband…
In order to investigate details of the superconducting (SC) gap in the iron-chalcogenide superconductors, the specific heat, C, of FeSe_1-x_Te_x_ with x=0.6-1 has been measured in magnetic fields. Using the two-gap model, it has been found…
We have studied the superconducting gap structure of LaPt$_2$Si$_2$ by measuring the temperature dependence of the London penetration depth shift $\Delta\lambda(T)$ and point contact spectroscopy of single crystals. $\Delta\lambda(T)$ shows…
We derive the extended Ginzburg-Landau (GL) formalism for a clean s-wave two-band superconductor by employing a systematic expansion of the free-energy functional and the corresponding matrix gap equation in powers of the small deviation…