A pinning puzzle: two similar, non-superconducting chemical deposits in YBCO—one pins, the other does not

Abstract

The pinning effects of two kinds of U-rich deposits in YBCO (YBa 2 Cu 3 O 7−δ ) are compared. One is a five-element compound, (U 0.6 Pt 0.4 )YBa 2 O 6 , which is a paramagnetic double perovskite which forms as profuse stable nanosize deposits, and pins very well. The other is a four-element compound, (U 0.4 Y 0.6 )BaO 3 , which is a ferromagnetic single perovskite which forms as profuse stable nanosize deposits and pins very weakly or not at all. The pinning comparison is done with nearly equal deposit sizes and number of deposits per unit volume for the two compounds. Evidence for the pinning capability, chemical makeup, x-ray diffraction signature, and magnetic properties of the two compounds is reported.