Large magnetoresistance effects near room temperature in manganite heterojunction

摘要

Magnetoresistive property of a heterojunction composed of Pr_(0.6)Ca_(0.4)MnO_(3) (PCMO) and Nb-doped SrTiO_(3) (STON) has been experimentally studied. A rather complex current-voltage relation characterized by the appearance of a low-bias electric breakdown prior to the reverse current saturation process is observed. The magnetic field shows a strong depression to this electric breakdown and, as a result, leads to a great change of junction resistance. It is interesting that the magnetoresistance thus produced, remains huge, ～1600% under a field of 5 T [defined as R(H)/R(0)-1], in a broad temperature range well above the Curie temperature of PCMO, which indicates a different mechanism of the magnetic field effect of PCMO/STON from other manganites and manganite-based heterojunctions. A qualitative explanation is given based on an analysis about the influence of interfacial defects on Hall electric field.