NONLINEAR ELECTRIC-RESPONSE OF YBA2CU4O8 CERAMICS AT THE INTERGRAIN SUPERCONDUCTIVE ORDERING

Linear and nonlinear electric response to the external AC current is o bserved in superconductive ceramics of a stoichiometric compound, YBa2 Cu4O8. A broad negative anomaly of a third-harmonic in-phase component V'(3 omega) is found around the inter-grain ordering temperature T-c2 determined by previous magnetic measurements. The anomaly gets remark able with decreasing AC current keeping the maximum position constant. From these results, a negative divergent anomaly of nonlinear electri c response is suggested as an intrinsic critical phenomenon of inter-g rain ordering in this system. (C) 1998 Elsevier Science B.V. All right s reserved.