Giant positive magnetoresistance in ferromagnetic manganites/silicon nanotips diode

The current-voltage relations and magnetotransport properties of La _0.7Sr _0.3MnO ₃/Si-nanotips and La _0.7Sr _0.3MnO ₃/Si-film junctions are studied, revealing that their transport properties are dominated by various mechanisms depending on temperature and bias voltage. A giant positive magnetoresistance (PMR) of ∼200% is observed at 40 K in La _0.7Sr _0.3MnO ₃/Si-nanotips junction. The temperature dependence of resistance in the presence of magnetic field suggests the origin of giant PMR to be the strong electron-electron interaction and electron-magnon scattering. Interestingly, such behavior is not observed in regular La _0.7Sr _0.3MnO ₃/Si-film junction, implying that the coupling between spin and charge could be greatly enhanced at the interface of La _0.7Sr _0.3MnO ₃ and Si nanotips.