No Arabic abstract
We have studied electrical transport properties of a high quality Bi2Sr2Ca2Cu3O10+x crystal below a superconducting critical temperature, Tc. In magnetic fields B parallel to the c-axis just above a voltage response onset resistance vs temperature data are well fitted to the vortex-glass model. Obtained from the vortex-glass analysis a melting transition boundary for Bi-2223 crystal shifted towards lower temperatures compared to previously reported data for a (Bi,Pb)-2223 single crystal. The critical current density, Jc, of Bi-2223 crystals is close to presented elsewhere Jc values for Bi-2223 tapes suggesting a principal role of weak intrinsic pinning properties of Bi-2223 as a main limiting factor of Jc of Bi-2223 conductors.
To investigate the origin of the enhanced Tc ({approx} 110 K) of the trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+{delta} (Bi-2223), its underdoped single crystals are a critical requirement. Here, we demonstrate the first successful in-plane resistivity measurements of heavily underdoped Bi-2223 (zero-resistivity temperatures {approx} 20~35 K). Detailed crystal growth methods, the annealing process, as well as X-ray diffraction (XRD) and magnetic susceptibility measurement results are also reported.
We report an experimental study of quench condensed ($2Kle T le 15K$) disordered ultrathin films of {rm Bi} where localisation effects and superconductivity compete. Experiments are done with different substrates and/or different underlayers. Quasi-free standing films of {rm Bi}, prepared by quenching {rm Bi} vapours onto solid {rm Xe}, are also studied. The results show a dependence of the transport properties both on the dielectric constant of the substrate/underlayer as well as the temperature of quench condensation. RHEED studies indicate that quantum size effects are important in these systems. In this paper, we try to correlate the structure of the films to the transport properties obtained.
We report the pressure effect in Bi2Sr2Ca2Cu3O10+{delta} (Bi-2223) single crystal with a small amount of intergrowth of Bi2Sr2CaCu2O8+{delta} (Bi-2212). Their superconducting transition temperatures Tcs showed a domelike shape as a function of pressure, which showed a good agreement with the general relation between the carrier concentration and Tc. Our experimental results indicate that high pressure can induce effective carrier doping into the multilayered high-Tc cuprate superconductor
We present the fabrication and electrical transport characterization of underdoped YBa$_2$Cu$_3$O$_{7-{delta}}$ nanowires. The nanowires have been realized without any protective capping layer and they show transport properties similar to those of the parent thin film, demonstrating that they have not been damaged by the nanopatterning. The current-voltage characteristics of the underdoped nanowires show large hysteretic voltage switching at the critical current, in contrast to the flux-flow like characteristics of optimally doped nanostructures, indicating the formation of a self-stabilizing hot spot. These results open up new possibilities of using the underdoped nanowires for single photon detection and for exploring the underdoped side of the YBa$_2$Cu$_3$O$_{7-{delta}}$ phase diagram at the nanoscale.
Sn0.8Ag0.2Te is a new superconductor with Tc ~ 2.4 K. The superconducting properties of Sn0.8Ag0.2Te have been investigated by specific heat measurements under magnetic fields. Bulk nature of superconductivity was confirmed from the amplitude of the specific heat jump at the superconducting transition, and the amplitude is consistent with fully-gapped superconductivity. Upper critical field was estimated from specific heat and electrical resistivity measurements under magnetic fields. The Hall coefficient was positive, suggesting that the Ag acts as a p-type dopant in Sn0.8Ag0.2Te.