Anomalous Hall coefficient in ceramic materials YBa2Cu3−xSnxO7+δ

The relations of a.c. susceptibility, a.c. resistance, remanent resistance (under a magnetic field) versus temperature and Hall coefficient (RH) in transition region have been investigated for 123 phase YBa2Cu3−xSnxO7+δ system. In normal state,RH is positive for the single phase samples with x=0.05, 0.1, 0.2 and 0.3, but negative for that with x=0.4 which contains impyrity phases. In superconducting transition region, a negativeRH peak is found for each of the single phase samples. Several situations are considered in the discussion of the origin of such anomalousRH, and it is suspected to be closely related to the anisotropy of the grain and itsRH.