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We study the two-component Ginzburg-Landau (GL) theory, in the presence of a self-consistent vortex line, to obtain the penetration depth (λ) and the effective healing length (ξ), in the asymptotic limit r → ∞. All these parameters versus T/Tc are analyzed for the materials MgB2, V3Si and LiFeAs in the interval 0.88 ≤ T/Tc ≤ 1.0, where the GL theory is assumed to be valid. We find that κ ≡ λ/ξ, which is another parameter not related to the GL parameter, is T-independent for V3Si and LiFeAs, while is T-dependent for the compound MgB2. This result suggests that even though all these three materials display two-gap superconductivity overall, near Tc superconductivity in V3Si and LiFeAs and seems to be different from the one in MgB2. The use of this parameter, κ, as a new way to " study" the superconducting materials, under the presence of a single vortex, is valid for 0.88Tc≲ T ≤ Tc, namely, in the GL formalism. [ABSTRACT FROM AUTHOR]

Abstract: Two previous models used with success in Cu-III-VI2 semiconductors have been employed to study the temperature dependence of the Urbach energy in ordered compounds Cu-III3-VI5 and Cu-III5-VI8. The model which contains two variable parameters seems to explain better the data over the whole temperature range studied. However, the ordered vacancy or the donor acceptor defect pair in the cation sublattice provides new features in these compounds that need further study. [Copyright &y& Elsevier]

We report measurements of the magnetic penetration depth lambda(T) in high-quality CePt3Si samples down to 0.049 K. We observe a linear temperature dependence below T approximately equal to 0.16Tc, which is interpreted as evidence for line nodes in the energy gap of the low-temperature phase of this material. A kink in lambda(T) at about 0.53 K may be associated with the second superconducting transition recently reported. The results are discussed in terms of the symmetry of the superconducting order parameter.