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The first harmonics of the magnetic response, of inter- and intragranular volume fractions of a FeSe0.5Te0.5 granular superconducting sample in an alternate magnetic field, have been numerically extracted from the measured magnetization of the whole system by using a model which considers the effects of the fundamental demagnetization fields generated by the magnetization itself. This allowed us to obtain the temperature and field behaviors of the inter- and intragranular ac losses during an ac cycle. These parameters have been found sensitive to the existence of the third harmonic components of the demagnetization field produced by the corresponding magnetization harmonics of the sample. This confirms that the effects of the magnetic response third harmonic components on the sample magnetization, through the demagnetization field, should be taken into account for a more detailed analysis of the measured ac magnetic curves. [ABSTRACT FROM AUTHOR]

The ferromagnetic transition temperature (Tc) of a weak ferromagnetic thin film Cu0.38Ni0.62 has been estimated by using an evolution of the Belov, Goriaga, and Arrott (BGA) model. In fact, the typically used measurements of the zero-field-cooled-field-cooled magnetic moment (m) as a function of temperature (T), the magnetic hysteresis loops (m(H)) as a function of field, and the temperature dependence of the remanent magnetic moment, performed on our sample, did not allow us to individuate precisely the value of Tc, mainly due to the influence of thermal effects and noise on the weak ferromagnetic response of the sample, resulting in a large uncertainty in the estimation of Tc. On the other hand, also the commonly used method of determining the Tc by means of a linear extrapolation of the high-field region of m2 as a function of the normalized magnetic field (H/m) at different temperatures (Arrott curves), working though for our analyzed material, could not completely fulfill the basic assumptions of the BGA model in general. For these reasons, we have considered the analysis of the derivatives of the Arrott curves, starting from observing that the Tc of the sample corresponds to the temperature where the curvature of the Arrott curves at low fields inverts. In this way, the sensitivity in the determination of the Curie point from the inductive measurements of the magnetic moment is improved while the correct assumptions of the Arrott model are also fully respected. [ABSTRACT FROM AUTHOR]

We report the experimental method of the evaluation of the specific boundary resistance, R, of superconductor (S)/non-superconductor (NS) interfaces by measuring the superconducting critical temperature, T, as a function of the thickness of the superconducting layer, d, in S/NS hybrids and of the number of S/NS bilayers, N, for a large number of N in NS/[S/NS] $_{N_{\mathrm{bl}}}$ multilayers. Two types of systems have been studied. We choose Nb as the S material for both types and Cu for a normal metal (N) for the first one. In the second case, a weakly ferromagnetic alloy (F), CuNi, was chosen for NS. Analyzing the experimental results by solving exactly the Usadel equations, we were able to unambiguously determine the value of R for both the S/N and S/F hybrids. The results show that Nb/Cu is characterized by a lower value of the interfacial specific resistance with respect to the case of Nb/CuNi. [ABSTRACT FROM AUTHOR]