Dependence of complex permeabiity and harmonic power generation of a sintered YBa 2Cu 3O 7−δ rod on applied AC and DC magnetic fields

Abstract

Systematic experimental studies are reported for the AC permeability and harmonic generation power P nf in a sintered rod of granular YBa 2Cu 3O 7−δ at 77 K as a unction of simultaneously applied AC and DC magnetic field from 0.01 to several hundred Oe. The separate contributions of the inter- and intragranular supercurrents are quite resolved, enabling the development of a generalized critical state model, which with two components is found to well explain the AC permeability and harmonic generation power as functions of AC and DC field up to the n=9 harmonic. Intergranular currents dominate the behavior for fields less than about 50 Oe; intragranular currents dominate for fields greater than 100 Oe.