The Low-Field Ac Impedance of YBa₂Cu₃O_7-δSuperconducting Slab

Abstract

R. Luxemburg str., 83114, Donetsk, UkraineUsing results of surface impedance measurements, the penetration of ac field into a melt-textured YBa 2 Cu 3 O 7−δ slab was investigated. We obtained a linear correlation between the surface impedance and ac frequency. The impedance curve shifts towards higher temperatures -0.9 K per decade of the frequency increase, for dc magnetic field µ0H dc ≤ 8 × 10 −3 T. This is an evidence of thermally activated flux creep. A plateau in the temperature dependence of the real impedance part was observed at approximately 88 K.