Positive magnetoresistance in heterostructure composed of two oxides

A positive magnetoresistance (MR) has been discovered in the epitaxial p-n heterostructure we fabricated with Sr-doped LaMnO3 and Nb-doped SrTiO3 by laser molecular-beam epitaxy. The MR dependence on the bias voltage has been displayed at the temperature of 130 and 190 K. The mechanism causing the unusual positive MR is proposed as the creation of the region near the interface with electron filling in the t2g spin-down band in La0.9Sr0.1MnO3. Other puzzling MR features with bias voltage, temperature are well explained by the present scenario.