相关论文: Electron diffusivities in MgB2 from point contact …
Angle-resolved soft x-ray measurements made at the boron K-edge in single crystal MgB2 provide new insights into the B-2p local partial density of both unoccupied and occupied band states. The strong variation of absorption with incident…
Superconducting mechanism mediated by interband exchange Coulomb repulsion is examined in an extended two-band Hubbard models with a wide band crossing the Fermi level and coexisting with a narrower band located at moderately lower energy.…
To understand the superconductivity in MgB2, several two-band models of superconductivity were proposed. In this paper, by using the relativistic fermion model, we clearize the effect of the lower band in the superconductivity.
The anisotropy gamma of the superconducting state of high quality single-crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature…
The temperature dependence of the upper critical field, Hc2, for both field directions in partially substituted polycrystalline MgB2 was determined. Whereas the suppression of Tc is similar for aluminum and carbon substituted samples, Hc2…
We present a numerical study of the field-angle resolved oscillations of the thermal conductivity and specific heat under rotated magnetic field in the $A_y$Fe$_{2-x}$Se$_2$ [$A$=K,Rb,Cs,(Tl,K)] superconductors, using realistic two-band…
We review recent measurements of upper (Hc2) and lower (Hc1) critical fields in clean single crystals of MgB2, and their anisotropies between the two principal crystallographic directions. Such crystals are far into the "clean limit" of…
We report on study of the electronic anisotropy of the newly discovered MgB2 superconductor using the in-plane resistivity measurements in magnetic field applied perpendicular and parallel to Mg and B planes of MgB2 single crystals. The…
The upper and lower critical field, and the critical field ratio of an anisotropic two-band magnetic superconductors in Ginzburg-Landau(GL) scenery is derived analytically. The temperature-dependent on the upper critical field is…
Directional point-contact Andreev-reflection spectroscopy measurements on the Ba$_{0.55}$K$_{0.45}$Fe$_2$As$_2$ single crystals are presented. The spectra show significant differences when measured in the $ab$ plane in comparison with those…
The upper critical field in MgB2 is investigated in the framework of the two-gap Ginzburg-Landau theory. A variational solution of linearized Ginzburg-Landau equations agrees well with the Landau level expansion and demonstrates that…
MgB$(p^{n_{\sigma}}p^{n_{\pi}})_{2}$ is classified as a system with strongly interacting $\sigma$-electrons and non-correlated $\pi$-electrons of boron ions. The kinematic and Coulomb interaction V between the orbitally degenerated…
Andreev reflection at the interface between a ferromagnet and a superconductor has become a foundation of a versatile new technique of measuring the spin polarization of magnetic materials. In this paper we will briefly outline a general…
We show how an electrical measurement can detect the pairing of electrons on the same side of the Fermi surface (Amperian pairing), recently proposed by Patrick Lee for the pseudogap phase of high-$T_c$ cuprate superconductors. Bragg…
We report the influence of intrinsic superconducting parameters on the vortex dynamics and the critical current densities of a MgB$_2$ thin film. The small magnetic penetration depth of \lambda = 50 nm at T=4 K is related to a clean…
We present a theoretical description of the differential conductance of point contacts between a normal metal and a multi-band superconductor with extended s\pm pairing symmetry. We demonstrate that the interband impurity scattering…
We present measurements of H$_{c2}(T)$ under pressure in MgB$_2$ and in YNi$_2$B$_2$C. The changes in the shape of H$_{c2}(T)$ are interpreted within current models and show the evolution of the main Fermi surface velocities $v_F$ and…
We study the excess conductance due to the superconducting proximity effect in a ballistic two-dimensional electron system subject to an in-plane magnetic field. We show that under certain conditions the interplay of the Zeeman spin…
The two-dimensional electron system in (110)Al$_2$O$_{3-\delta}$/SrTiO$_3$ heterostructures displays anisotropic electronic transport. Largest and lowest conductivity and electron mobility $\mu$ are observed along the $[001]$ and…
Measurements of x-ray emission and absorption spectra of the constituents of MgB$_2$ are presented. The results obtained are in good agreement with calculated x-ray spectra, with dipole matrix elements taken into account. The comparison of…