ANOMALOUS MAGNETORESISTANCE IN BULK POLYCRYSTALLINE Y1BA2CU3O7-D

The nature of the resistive transition of bulk YBCO samples in low d.c . magnetic fields was investigated. Just below the phase transition on set, the under-field resistance becomes notably higher than the resist ance prior to field application. In addition a difference between the resistance after field removal and the resistance prior to its applica tion is also observed. Over part of the temperature range, this resist ance exhibits anomalous negative remanent magnetoresistance. A qualita tive interpretation is proposed.