Correlation of magnetoresistance and lateral photovoltage in Co ₃Mn₂O/SiO₂/Si metal-oxide-semiconductor structure

Though separate studies on the individual properties of photovoltage and magnetoresistance (MR) have made much progress, work integrating the two phenomena into one kind of structure has not been reported so far. This study combines MR and lateral photovoltage (LPV) in a magnetic oxidized film Co ₃Mn₂O deposited on an n-type Si substrate with a native ultrathin SiO₂ surface by sputtering. The effective resistance shows a marked transition for temperature around 240K. Both negative MR {MR= [R(H)- R(0)]/R(0) × 100%} of -11% at 4.2 K and a large positive MR of 70% at 300 K at a magnetic field of 6 T were observed. This phenomenon can be explained by the conducting channel switching from the upper film to the Si inversion layer. Under the nonuniform illumination of a laser beam, the LPV shows a high sensitivity to the spot position on the Co₃Mn₂O film plane. The current-voltage (I-V) characteristic of the Co₃Mn ₂O/SiO₂/Si metal-oxide-semiconductor (MOS) structure exhibits rectifying I-V behavior, which suggests that the lateral photoeffect (LPE) can be interpreted in terms of the metal-semiconductor (MS) junction that exists between the magnetic film and silicon substrate. When an external magnetic field is applied perpendicular to the film, the LPV shows a monotonic increase with increasing magnetic field. The variation of LPV reaches 93.2% at 2 T. This intriguing effect may be due to the Lorentz force acting on the photo-generated carriers.