相关论文: The upper critical field problem in MgB2

We studied a method of measuring upper critical field (H$_{c2}$) of a superconductor based on the width of $\Delta$H = $\Delta$B region, which appears in the superconductor that volume defects are many and dominant. Here we present the…

The bulk upper critical field H_{c2}(T) of superconducting MgB_2 and its anisotropy are established by analyzing experimental data on the temperature and magnetic field dependences of the ab-plane thermal conductivity of a…

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 measurements of the superconducting critical temperature Tc and upper critical field Hc2 as a function of pressure in the transition metal dichalcogenide 2H-NbS2 up to 20 GPa. We observe that Tc increases smoothly from 6K at…

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 study the problem of the upper critical field ($H_{c2}$) for tight-binding electrons in a two-dimensional lattice. The external magnetic field is introduced into the model Hamiltonian both via the Peierls substitution and the Zeeman…

Detailed Fermi-surface structures are essential to describe the upper critical field $H_{c2}$ in type-II superconductors, as first noticed by Hohenberg and Werthamer [Phys. Rev. {\bf 153}, 493 (1967)] and shown explicitly by Butler for…

We report first-principles calculations of the k- and T-dependent superconducting gap Delta(k,T) in MgB2 and its manifestation in various measured quantities. Because the Fermi surface has disconnected sheets with different electron-phonon…

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…

We perform calculations to obtain the $H_{c2}$ curve of high temperature superconductors (HTSC). We consider explicitly the fact that the HTSC possess intrinsic inhomogeneities by taking into account a non uniform charge density $\rho(r)$.…

The upper critical fields ($H_{c2}$) of the single crystals $\rm(Sr,Na)Fe_2As_2$ and $\rm Ba_{0.55}K_{0.45}Fe_2As_2$ were determined by means of measuring the electrical resistivity, $ \rho_{xx}(\mu_0H)$, using the facilities of pulsed…

The superconducting upper critical field $H_{c2}(T)$ of a two dimensional BCS superconductor is calculated in the vicinity of a van-Hove singularity. The zero temperature upper critical field is strongly enhanced at weak coupling when the…

Temperature dependence of the upper critical field Hc2 (T) for the superconducting magnesium diboride, MgB2, is studied in the vicinity of Tc by using a two-band Ginzburg-Landau (G-L) theory. The temperature dependence of Hc2 (T) near Tc…

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…

The theory of thermodynamic properties of two-band superconductor with reduced density charge carriers is developed on the base of phonon superconducting mechanism with strong electron-phonon interaction. This theory is adapted to describe…

An overview of the theory of the upper critical field in dirty two-gap superconductors, with a particular emphasis on MgB$_2$ is given. We focus here on the maximum $H_{c2}$ which may be achieved by increasing intraband scattering, and on…

Here we report the comparison of the upper critical fields of different superconductors being calculated by two different theories i.e., Werthamer Helfand Hohenburg (WHH) and Ginzberg Landau (GL). All the samples are synthesized through…

We present a detailed numerical calculation of the upper critical field $H_{c2}(T)$ for a bulk extreme type-II superconductor. Particular emphasis is placed on the high-field, low-temperature regime of the HT-phase diagram. In this regime…

We present new upper critical field Hc2(T) data in a broad temperature region from 0.3K to Tc for LuNi2B2C and YNi2B2C single crystals with well characterized low impurity scattering rates. The absolute values for all T, in particular…

We study the upper critical field of the A and B phases in the triplet superconductor PrOs_{4}Sb_{12} within the p+h-wave superconductivity proposed recently for this material. The present result is compared with H_{c2}(t) and H*(t), the…