Pressure and Grain-Size Dependences of the Chiral-Glass Transition in Superconductive Ceramics of YBa_(2)Cu_(3)O_(7-y)

摘要

Ceramic high-T_(c) superconductors may be viewed as a weakly coupled random Josephson network containing π-junctions, and a chiral-glass transition is predicted to be occurred. Grain-size and pressure dependences of the chiral-glass transition have been investigated on YBa_(2)Cu_(3)O_(7-y) ceramics. With decreasing temperature, a superconducting order occurs at first inside each grain at T_(c1) and furthermore among the grains at T_(c2) (