Magnetically Tunable Depletion Layer in Manganite-Titanate Heterojunctions

A significant effort has been put toward the realization of oxide heterojunction devices, as well as understanding the electronic structure of interfaces between Mott insulators and band insulators. The manganite-titanate heterojunction is an attractive candidate in this context. Perovskite manganites have a versatile range of magnetic and electronic properties related to orbital, charge and spin order, such as colossal magnetoresistance (CMR) and metal-insulator transitions. Here we present rectification in this manganite-based heterojunction, demonstrating a magnetically tunable depletion layer. The magnetic field increases the junction capacitance due to the reduction of the effective depletion width across the junction. As a result of the reduction of the junction barrier, the forward bias I-V characteristics are shifted to lower voltage under a magnetic field, giving rise to exponential differential magnetoresistance.