Rectifying characteristics and tunable magnetoresistance in heterojunctions of La0.9Hf0.1MnO3/0.05 wt.% Nb-doped SrTiO3

La0.9Hf0.1MnO3 films were grown on 0.05 wt.% Nb-doped SrTiO3 substrates by pulsed laser deposition. X-ray diffraction measurements demonstrated that our samples were of good epitaxy and single-crystal. The temperature-dependent resistance has been investigated. It was observed that the as-grown film of La0.9Hf0.1MnO3 exhibited a typical paramagnetic-ferromagnetic transition. Heterojunctions of La0.9Hf0.1 MnO3/0.05 wt.% Nb-doped SrTiO3 exhibited-asymmetric current voltage characteristics and a remarkable temperature-dependent rectifying behavior in a wide temperature range (from 40 K to 300 K). And the most remarkable observation of this work is the existence of a crossover from positive to negative magnetoresistance in the La0.9Hf0.1MnO3/0.05 wt.% Nb-doped SrTiO3 heterojunction as the temperature decreases. A temperature-dependent magnetoresistance was studied as well. The rectifying characteristics and tunable magnetoresistance of these heterojunctions may be attributed to band structure of La0.9Hf0.1MnO3/0.05 wt.% Nb-doped SrTiO3 heterojunction.