Related papers: Electron diffusivities in MgB2 from point contact …
The results of the first directional point-contact measurements in MgB2 single crystals, in the presence of magnetic fields up to 9 T either parallel or perpendicular to the ab planes, are presented. By applying suitable magnetic fields, we…
Magnesium diboride MgB2 has been an extraordinarily hot research topic since the discovery of superconductivity below 40 K, due to the vast amount of unusual properties originating from the involvement in superconductivity of two sets of…
We studied the voltage and temperature dependency of the dynamic conductance of normal metal-MgB2 junctions obtained either with the point-contact technique (with Au and Pt tips) or by making Ag-paint spots on the surface of high-quality…
Recent experimental data of anisotropic magnetoresistivity measured in MgB2 films have shown an intriguing behaviour: the angular dependence of magnetoresistivity changes dramatically with temperature and disorder. In order to explain such…
We have performed differential conductance versus voltage measurements of Au/MgB2 point contacts. We find that the dominant component in the conductance is due to Andreev reflection. The results are fitted to the theoretical model of BTK…
Recent measurements of the anisotropy of the upper critical field Bc2 on MgB2 single crystals have shown a puzzling strong temperature dependence. Here, we present a calculation of the upper critical field based on a detailed modeling of…
Based on a detailed modeling of the Fermi surface topology of MgB2 we calculated the anisotropy of the upper critical field Bc2 within the two gap model. The sigma-band is modeled as a distorted cylinder and the pi-band as a half-torus,…
We present the results of directional point-contact measurements in MgB_2 single crystals, in magnetic fields up to 9 T parallel to the c axis. By fitting the conductance curves of our point contacts -- showing clear Andreev-reflection…
The results of first principles calculations of the electronic structure and the electron-phonon interaction in MgB2 are used to study theoretically the temperature dependence and anisotropy of the magnetic field penetration depth. The…
A brief review of works on the microscopic theory of determining the upper critical field in two-band isotropic and anisotropic superconductors is given. The research is based on a set of the Ginzburg-Landau equations for the order…
The upper critical field Hc2 is evaluated for weakly-coupled two-band superconductors. By modeling the actual bands and the gap distribution of MgB2 by two Fermi surface spheroids with average parameters of the real material, we show that…
Experimental support is found for the multiband model of the superconductivity in the recently discovered system MgB2 with the transition temperature Tc = 39 K. By means of Andreev reflection evidence is obtained for two distinct…
A series of calculations on MgB2 and related isoelectronic systems indicates that the layer of Mg(2+) ions lowers the non-bonding B "pi" (p_z) bands relative to the bonding "sigma" (sp_xp_y) bands compared to graphite, causing sigma --> pi…
We show that a two-band model with ${\bf k}$-dependent superconducting gaps well describes the transmission and optical conductivity measured for MgB$_2$ thin films. It is also shown that the two-band anisotropic model consistently…
The study of the anisotropic superconductor MgB2 using a combination of scanning tunneling microscopy and spectroscopy reveals two distinct energy gaps at Delta1=2.3 meV and Delta2=7.1 meV. Different spectral weights of the partial…
We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB_2 single crystals. Due to the directionality of the current injection into the samples, the application of a magnetic field allowed…
The angular and temperature dependence of the upper critical field Hc2 in MgB2 was determined from torque magnetometry measurements on single crystals. The Hc2 anisotropy gamma_H was found to decrease with increasing temperature, in…
This paper presents a brief review on the reported anisotropic properties of MgB2, in the superconducting state (e.g. upper critical field Hc2, field penetration depth, coherence length, energy gap) as well as in the normal state (e.g.,…
The anisotropy of the London penetration depth is evaluated for two-band superconductors with arbitrary inter- and intra-band scattering times. If one of the bands is clean and the other is dirty in the absence of inter-band scattering, the…
Detailed temperature dependence of both superconducting gaps was obtained directly by means of SnS-Andreev spectroscopy. The \Delta \sigma,\pi(T) -curves were shown to be deviated from standard BCS-like behavior, due to k-space proximity…