Magnetocapacitance and exponential magnetoresistance in manganite-titanate heterojunctions

We present a rectifying manganite-titanate heterojunction exhibiting a magnetic field tunable depletion layer. This creates a large positive magnetocapacitance, a direct measure of the field-induced reduction of the effective depletion width across the junction. Furthermore, the reduction of the junction barrier shifts the forward bias characteristics, giving exponentially enhanced differential magnetoresistance, occurring despite the absence of a spin filter. These results provide a unique probe of a Mott insulator/band insulator interface, and further suggest electronic devices incorporating the magnetic field sensitivity of these strongly correlated electron materials. (c) 2005 American Institute of Physics.