Magnetoresistance and photoelectrical properties of electron gases at SrTiO₃ (1 0 0) surface

Electron gases are created at (1 0 0)-oriented SrTiO3 (STO) surfaces by being irradiated with high-speed Ar+ ions. Although fully metallic behavior is observed in both samples, the electron gases at STO surfaces bombarded with acceleration voltage of 200 V (sample L) show smaller carrier density and lower mobility than those at STO surfaces with 400 V acceleration voltage (sample H). Light related magnetoresistance (MR) and magnetic related photoelectrical properties for electron gases at STO surfaces are compared between sample L and sample H, respectively. Under light illumination, sample L shows increased positive MR, which decreases in sample H. Furthermore, the photoconductivity for sample L becomes slightly smaller and that for sample H rises obviously when the magnetic field is applied. The physical mechanisms responsible for the distinct behavior between the samples have been discussed.