CPP transport properties of polycrystalline Fe₃O₄ thin films sputtered on Cu underlayers

Transport properties of sputtered Fe₃O₄ thin films have been studied with the current perpendicular to plane (CPP) configuration. Fabricated polycrystalline Fe₃O₄ films exhibit superior CPP conductivity of 12 kΩ^-1∙m^-1. In addition to the Verwey transition (VT), observed at 114 K, another type of drastic conductivity change [field induced transition (FT)] was observed at lower temperature (T≪70 K) and higher bias voltage (V_b≫0.18 V) regime. The conductivity change at FT is discontinuous and several orders in magnitude. The transition temperature for FT presents considerable V_b dependence, contrarily no distinguished dependence for VT.