Irreversibility effects in polycrystalline high-Tc superconductors studied by AC susceptibility

P. LEVY, H. FERRARI, C. ACHA, V. BEKERIS

PHYSICA C - SUPERCONDUTIVITY

ELSEVIER SCIENCE BV

Lugar: New York; Año: 1994 vol. 222 p. 212 - 218

0921-4534

AbstractLocal magnetic-field effects in the high-Tc polycrystalline superconductor La1.8Sr0.2CuO4-δ were studied by means of AC susceptibility measurements with a superimposed DC magnetic field, which has proven to be a sensitive technique for detecting intergranular screening currents. Measurements were performed in different magnetic configurations, obtained by cycling the DC field. The effect of intragrain pinned vortices on the intergranular local field was examined. Experimental data were analyzed using intergranular and intragranular critical-state models. Irreversible paths are discussed. We show that the Bean model applied to superconducting grains explains qualitatively the hysteretic behavior found after cycling the DC field to different maximum values for the first and second time.