Resistive hysteresis and capacitance effect in NiFe_2O_4/SrTiO_3: Nb(l wt%) junctions

摘要

Epitaxial ultrathin NiFe_2O_4 films were deposited on 1 wt% Nb-doped SrTiO_3 (001) substrates by reactive cosputtering to form junctions with an area of ~2 mm2, and current-voltage curves show rectifying and asymmetrical hysteresis characteristics. The resistance calculated from the current-voltage curves is strongly voltage dependent, and the hysteretic loops with high and low resistive states were observed. The hysteretic loops are considered to stem from the capacitance effect of the highly resistive NiFe_2O_4 layer, which leads to charge accumulation at the interfaces. The results show that the interfaces of the junctions have a large areal capacitance of ~100 nF/mm~2 from 300 to 120 K.