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Magnetic-field dependence of the ac susceptibility in granular YBa 2 Cu 3 </…

1991; American Physical Society; Volume: 43; Issue: 13 Linguagem: Inglês

10.1103/physrevb.43.11404

1095-3795

Youngtae Kim, Q. H. Lam, C. D. Jeffries,

Magnetic and transport properties of perovskites and related materials

For a sintered rod of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ at 78.3 K, detailed data are reported for the complicated dependence of the ac susceptibility \ensuremath{\chi}\ifmmode \tilde{}\else \~{}\fi{}=\ensuremath{\chi}'-i\ensuremath{\chi}'' on applied ac and dc fields, ascribed to the inter- and intragranular components of the material. The intergranular data are understood in detail by a modified critical-state model, assuming a critical current density ${\mathit{J}}_{\mathit{c}}$(H)\ensuremath{\sim}${\mathit{H}}^{\mathrm{\ensuremath{-}}2}$. $chi tilde (H sub roman dc )--- also displays hysteresis which is not readily explicable by this model.