Possible Evidence for Superconducting Layers in Single Crystal YBa2Cu3O7-x by Field Ion Microscopy
A. J. MELMED 1,
R. D. SHULL 1,
C. K. CHIANG 1, and
H. A. FOWLER 1
1 National Bureau of Standards, Gaithersburg, MD 20899.
The high-transition-temperature superconducting ceramic material YBa2Cu3O7-x (0< x < 0.5) has been examined by field ion microscopy. Specimens from nominally superconducting and nonsuperconducting samples(determined by magnetic susceptibility measurements) were studied by field ion microscopy and significant differences were found. Preferential imaging of atomic or molecular layers, due to preferential field evaporation, field ionization, or both, was found in the superconducting phase below the transition temperature and is interpreted as possible evidence for the occurrence of relatively highly conducting layers in the YBa2Cu3O7-x unit cell perpendicular to the orthorhombic c-axis. Similar results were obtained for YbBa2Cu37-x.
Submitted on October 26, 1987
Accepted on November 26, 1987
