Effect of charge order transition on tunneling resistance in Pr_0.6Ca_0.4MnO₃/Nb-doped SrTiO₃ heterojunction

An oxide p-n heterojunction composed of Pr_0.6Ca_0.4MnO₃ film, with a charge order (CO) transition, and 1wt% Nb-doped SrTiO₃ substrate is fabricated, and the transport properties of the interface are experimentally studied. The rectifying behavior of the junction, well described by the Newman equation, is observed, indicating that tunneling is the dominant process by which the carriers pass through the interface. Above and below the CO transition temperature, satisfactory linear dependencies of junction resistance on temperature are observed, but the slopes of the two resistance-temperature relations are different. The CO process is believed to be relevant to this difference.