Related papers: Two-gap superconductivity in MgB$_{2}$: clean or d…
We report scanning tunneling spectroscopy (STS) measurements of the gap properties of both ceramic MgB2 and c-axis oriented epitaxial MgB2 thin films. Both show a temperature dependent zero bias conductance peak and evidence for two…
The free energy, non-gradient terms of the Ginzburg-Landau expansion, and the jump of the specific heat of a multiband anisotropic-gap clean BCS superconductor are derived in the framework of a separable-kernel approximation. Results for a…
The structure of the superconducting gap provides important clues on the symmetry of the order parameter and the pairing mechanism. The presence of nodes in the gap function imposed by symmetry implies an unconventional order parameter,…
We study a two-band Hubbard model using the dynamical mean-field theory combined with the exact diagonalization method. At the electron density $n=2$, a transition from a band-insulator to a correlated semimetal occurs when the on-site…
``Sub-meV'' resolution photoemission spectroscopy was used to study carbon-substitution dependence on the multiple superconducting gap of Mg(B$_{1 - x}$C$_{x})_{2}$. Two features corresponding to $\sigma $ and $\pi $ gaps are clearly…
Case studies of $1T$-TiSe$_2$ and YBa$_2$Cu$_3$O$_{7-\delta}$ have demonstrated that x-ray diffraction (XRD) studies can be used to trace even subtle structural phase transitions which are inherently connected with the onset of…
Quasiclassic Uzadel equations for two-band superconductors in the dirty limit with the account of both intraband and interband scattering by nonmagnetic impurities are derived for any anisotropic Fermi surface. From these equations the…
Based on experimental results and our previous theoretical work, a microscopic theory of high temperature superconductivity is conjectured. In this conjecture, superconducting and antiferromagnetic long-range orders are driven by interlayer…
We present the ultralow-temperature thermal conductivity measurements on single crystals of transition-metal dichalcogenide material 4Hb-TaS$_{2}$, which has recently been proposed as a topological superconductor candidate. In zero field, a…
The microscopic superconductivity theory in MgB2 systems in the magnetic fields directed parallel and perpendicular to the plane (ab) is built. The two energy bands of different dimensions overlapping on the Fermi surface (two-dimensional…
The ab-plane thermal conductivity $\kappa$ of single-crystalline hexagonal MgB_2 has been measured as a function of magnetic field H with orientations both parallel and perpendicular to the c-axis and at temperatures between 0.5 and 300 K.…
We report the first study of the optical conductivity of MgB2 covering the range of its superconducting energy gap. Terahertz time-domain spectroscopy is utilized to determine the complex, frequency-dependent conductivity of thin films. The…
This review paper illustrates the main normal and superconducting state properties of magnesium diboride, a material known since early 1950's, but recently discovered to be superconductive at a remarkably high critical temperature Tc=40K…
We report data on the thermal conductivity K(T,H) along the basal plane of the hexagonal crystal structure of superconducting Mg{1-y}Al{y}B2 with y=0.02 and 0.07 at temperatures between 0.5 and 50 K and in external magnetic fields between 0…
We studied the temperature dependences of the optical spectra for optimally and underdoped Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+z}$ single crystals. Similarly to the other cuprates' cases, a gap-like conductivity suppression was observed with…
Superconducting micro-constrictions between Nb tips and high quality MgB$_{2}$ pellets have been realized by means of a point-contact inset, driven by a micrometric screw. Measurements of the current-voltage characteristics and of the…
The progress in investigation of two-band superconductor MgB$_2$ by the point-contact spectroscopy (PCS) is given. Results of study of superconducting gap temperature and magnetic field dependence for two-dimensional $\sigma$ and…
Superconductivity in Pb, H under extreme pressure and CaBeSi, in the framework of the density functional theory for superconductors, is discussed. A detailed analysis on how the electron-phonon and electron-electron interactions combine…
The model of hypothetical superconductivity, where the energy gap asymptotically approaches zero as temperature increases, has been proposed. Formally the critical temperature of such a superconductor is equal to infinity. For practical…
Recent experimental data (H. Nam et al., Phys. Rev. B 100, 094512 (2019)) of critical temperature and gaps measured on superconductor/normal metal heterostructure Pb/Ag, epitaxially grown, shown a interesting not usual behaviour. The…