Observation of granular superconductivity in polycrystalline Sm2-xCexCuO4-y

Using field-dependent (0 less than or equal to B less than or equal to 7 T) noncontact rf surface-resistance measurements, we confirm the onset of granular superconductivity in the high-temperature superconductor Sm2-xCexCuO4-y, 0.15 less than or equal to x less than or equal to 0.18 at temperatures for which there is no evidence for a bulk Meissner effect. The surface-resistance data are described with an extended form of the Coffey-Clem theory. For the samples with x=0.15, these measurements also indicate that near the mean-field critical temperature T-c, -dB(c2)(c)/dT congruent to 0.38 T/K, for B parallel to c axis. [S0163-1829(98)04606-2].