Enhancement of the critical current density of YBa2Cu3Ox superconductors under hydrostatic pressure.

The dependence of the critical current density Jc on hydrostatic pressure to 0.6 GPa is determined for a single 25 degrees [001]-tilt grain boundary in a bicrystalline ring of nearly optimally doped melt-textured YBa2Cu3Ox. Jc is found to increase rapidly under pressure at +20%/GPa. A new diagnostic method is introduced (pressure-induced Jc relaxation) which reveals a sizable concentration of vacant oxygen sites in the grain boundary region. Completely filling such sites with oxygen anions should lead to significant enhancements in Jc.

Superconducting gap in bi-sr-ca-cu-o by high-resolution angle-resolved photoelectron spectroscopy.

Detailed studies indicate a superconducting gap in the high-temperature superconductor Bi(2)Sr(2)CaCu(2)O(8). Photoemission measurements with high energy and angle resolution isolate the behavior of a single band as it crosses the Fermi level in both the normal and superconducting states, giving support to the Fermi liquid picture. The magnitude of the gap is 24 millielectron volts.