Magnetic and transport properties in metal-oxide-semiconductor structures of Co3Mn2O/SiO2/Si

Magnetic and transport properties were investigated in metal-oxide-semiconductor structures of Co3Mn2O/SiO2/Si prepared by the dc magnetron sputtering technique. Magnetic studies reveal that Co3Mn2O is a granular film consisting of CoO, MnO, Co and Mn. The effective resistance shows a marked transition for temperature at around 240 K. Both negative magnetoresistance {MR = [R(H) - R(0)]/R(0) X 100%} of -11% at 4.2 K and a large anomalous positive magnetoresistace of 70% at 300 K at a magnetic field of 6 T were observed. These phenomena can be explained by the conducting channel switching from the upper film to the Si inversion layer.