相关论文: Orbital upper critical field of type-II supercondu…
Since the discovery of high-temperature superconductivity in cuprates, understanding the unconventional pairing mechanism has remained one of the most significant challenges. The upper critical field ($H_{\rm{c2}}$) is an essential…
The upper critical field $H_{c2} $, the field $H_{c3}$ for nucleation of the surface superconductivity, and the thermodynamic $H_c $ are evaluated within the weak-coupling theory for the isotropic s-wave case and arbitrary transport and…
We calculate the upper critical field, Hc2(T), due to the orbital pair breaking in disordered superconductors without inversion symmetry. Differences from the usual centrosymmetric case are highlighted. The linearized gap equations in…
The Helfand-Werthamer (HW) scheme\cite{HW} of evaluating the orbital upper critical field is generalized to anisotropic superconductors in general, and to two-band clean materials, in particular. Our formal procedure differs from those in…
The upper critical fields, Hc2 of single crystals of Sr1-xEux(Fe0.89Co0.11)2As2(x=0.203 and 0.463) were determined by radio frequency penetration depth measurements in pulsed magnetic fields. Hc2 approaches the Pauli limiting field but…
The upper critical field $\mu_0H_{c2}(T_c)$ of Tl$_{0.58}$Rb$_{0.42}$Fe$_{1.72}$Se$_2$ single crystals has been determined by means of measuring the electrical resistivity in both a pulsed magnetic field ($\sim$60T) and a DC magnetic field…
The upper critical fields ($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 purpose of this research is to study the upper critical field (Hc2) of two-band superconductors by two-band Ginzburg - Landau approach. The analytical formula of Hc2 included anisotropy of order parameter and anisotropy of…
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…
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…
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…
Measurements of temperature-dependent in-plane resistivity, $\rho(T)$, were used to determine the upper critical field and its anisotropy in high quality single crystals of stoichiometric iron arsenide superconductor KFe$_2$As$_2$. The…
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…
The in-plane magnetoresistance of an epitaxial Bi$_2$Sr$_2$CuO$_{6+\delta}$ thin film was systematically investigated as a function of doping, above $T_c$. The orbital magnetoconductance is used to extract the crossover field line…
We report a significant enhancement of the upper critical field $H_{c2}$ of different $MgB_2$ samples alloyed with nonmagnetic impurities. By studying films and bulk polycrystals with different resistivities $\rho$, we show a clear trend of…
The upper critical field $H_{c2}$ is one of the many non conventional properties of high-$T_c$ cuprates. It is possible that the $H_{c2}(T)$ anomalies are due to the presence of inhomogeneities in the local charge carrier density $\rho$ of…
The upper critical field $H_{c2}$ of purple bronze Li$_{0.9}$Mo$_6$O$_{17}$ is found to exhibit a large anisotropy, in quantitative agreement with that expected from the observed electrical resistivity anisotropy. With the field aligned…
The upper critical field of NaFe$_{1-x}$Co$_x$As was measured from $x=0$ to $x=0.08$, with the magnetic field applied parallel ($H_{\rm c2}^\parallel$) and normal ($H_{\rm c2}^\perp$) to the planes. The data were fitted using one-band and…
The BCS picture of superconductivity describes pairing between electrons originating from a single band. A generalization of this picture occurs in multi-band superconductors, where electrons from two or more bands contribute to…
It is demonstrated that the slope of the upper critical field $|dH_{c2}/dT|_{T_{c}}$ in superconductors with $d$-wave pairing drops rather fast with concentration of normal impurities, while in superconductors with anisotropic $s$-wave…