[en] We have investigated the transport and magnetic properties of the RCu (R=La, Ce, Pr and Nd) systems by means of the ac electrical resistivity ρ and dc magnetization χ measurements. For LaCu, bulk superconductivity is observed with a superconducting transition temperature of 6.15 K as inferred from a sudden drop to zero value in the ρ(T) curve and the diamagnetic behavior in the χ(T) curve. The occurrence of a peak in the χ(T) curve and a drop off in the ρ(T) curve indicate that antiferromagnetic transition occurs in CeCu and NdCu with transition temperatures T_N of 3.72 and 10 K, respectively. A magnetization study reveals that an antiferromagnetic transition occurs at T_N∼13 K for PrCu. ((orig.))

[en] Bulk and tape specimens of Nb₃Al have been fabricated by the powder metallurgy method between Nb₂Al and Nb. The microstructure and superconducting properties on the starting materials and the temperature of a heat treatment have been studied. X-ray diffraction analysis was carried out in order to identify the phases formed by the heat treatment. The A15 single phase, Nb₃Al, were formed at 1100degC for the bulk specimen prepared from the Nb₂Al/Nb mixed powders. The temperature of a heat treatment formed the A15 single phase prepared from the Nb₂Al/Nb was down 100-200degC in comparison to that prepared from the Nb/Al mixed powders. The highest critical temperature, Tc, obtained in the bulk specimens prepared from the Nb₂Al/Nb mixed powders is 16.0 K. (author)

[en] The effect of tension deformation at 4,2 K with subsequent warming to room temperature upon the defective structure and the superconducting transition temperature T_c of electron-beam melted zirconium is studied. The appreciable increase in T_c (be 20%) is due to enhanced superconductivity at the sites of localized plastic strain at the twin boundaries and is connected with the effective change of the electron attraction constant

[en] Superconducting properties, such as the isotopic shift factor for the critical temperature TS, the dependence of the order parameter ΔS on the coupling constant and the upper critical magnetic field Hc2dj, for amorphous metals with quantum defects of the hydrogen type are discussed. The role of the electron-polaron effect is analyzed in the adiabatic approach

[en] Interplay between superconductivity (SC) and ferromagnetism (FM) in dilute magnetic alloys and intermetallic compounds attracted considerable attention during the last 30 years. Usually the FM state is more stable and therefore tends to suppress SC. On the other hand, the magnetic state can be changed due to a modification of the RKKY interaction in the SC state. Mutual influence of SC and FM may acquire new peculiarities in such artificial systems as FM/SC multilayers. This work is focused on the study of Fe/Nb multilayered system, prepared on Al₂O₃(11 bar 20) substrates by rf-sputtering and by molecular beam epitaxy (MBE) techniques. The Nb thickness t_Nb was varied from 150 to 500 A and the Fe thickness t_Fe was changed from 5 to 100 A. The sputtered samples were highly layered with sharp interfaces as revealed by x-ray reflectivity and were textured in the [110] direction. The epitaxial MBE samples showed (110) growth of Nb and Fe with a coherence lengths comprising the total film thickness. Surface and interface roughnesses were very small. The dependence of the ferromagnetic resonance (FMR) spectra parameters on the direction of the dc magnetic field rotating in the plane of the samples show sixfold anisotropic behavior indicating the well known three-domain in-plane structure of Fe layers on sapphire substrates. FMR and SQUID measurements showed that FM of Fe layers survived down to t_Fe=10 A. The out-of-plane FMR measurements also showed that the easy axis of magnetization lies in the plane of the samples down to this thickness. The superconducting transition temperature T_c was determined by measurements of the electrical resistivity and by SQUID measurements. It was established that there is a critical thickness of the Fe layer t_Fe^crit above which SC was not detected for temperatures down to 1.5 K. This value was dependent on t_Nb. (Abstract Truncated)

[en] We present simulations of vortex dynamics in amorphous two-dimensional thin film superconductors, using a new exact method to evaluate long-range interactions between vortices. We find that the onset of dissipation for increasing current is dominated by filamentary channels of flow which are stable in a finite range of bias current. This results in novel steps in the differential resistance, which are strongly history dependent. Our results are in good agreement with recent experiments on amorphous Mo₇₇Ge₂₃ superconducting thin films. copyright 1996 The American Physical Society

[en] Impact of passing high-density electric current at the temperature of 78 K on electrophysical properties of YBa₂Cu₃0_7-x films is studied. The experimental data obtained show that sublayer defects constitute one of the causes of the YBa₂Cu₃0_7-x films degradation. 10 refs

[en] Short communication. 4 refs., 2 figs

[en] Published in summary form only

[en] We present measurements of longitudinal ultrasound in UPt₃ along both the a- and c-axis in the region of the two superconducting transitions, Tc₊ and Tc_*. Using expressions from a model for the double superconducting transition, our measurements constrain the strain-dependences of a number of parameters. In particular, these constraints imply that the observed anisotropy in the stress-dependence of Tc_* results from anisotropy in the elastic compliance tensor, rather than anisotropy of the superconducting order parameter. We also report an anomalous lattice softening below 100 mK. (orig.)