Synthesis of YNi2B2C thin films by magnetron sputtering

Thin films of YNi2B2C superconductor by the magnetron sputtering technique have been synthesized. The YNi2B2C phase was found to crystallize very uniformly after annealing at 1050 °C in vacuum. The structure was investigated and the electric and magnetic properties were characterized. The films were c-axis oriented and showed a Tc onset of ~15 K by both magnetization and resistivity measurements. The results of the critical current measurement suggested the existence of anisotropies of pinning force and an upper critical field Bc2

Vortex states of Bi2Sr2CaCu2O8+y with antidot array probed by c-axis transport measurements

AbstractTo study the vortex states in Bi2Sr2CaCu2O8+y (Bi2212) high-Tc superconductor with periodic array of antidots, we have measured the c-axis critical current in a stack of the intrinsic Josephson junctions with a square lattice of antidots, which gives us information on the c-axis correlation of the pancake vortices. Without the antidot array, the c-axis critical current can probe the first-order vortex lattice melting transition. Additionally, a suppression of the critical current in the vicinity of zero magnetic field is found, which may be related to the instability of vortex lattice under the parallel current flow. With the square lattice of antidots, enhancements of the critical current due to the matching effect are observed in both the integer and fractional matching fields. By mapping the critical current on H-T diagram, the influence of the matching effect on the phase boundary of vortex solid and liquid is shown