Magnetoresistance and Hall effect in Co implanted GaAs hybrid magnetic semiconductors

The hybrid Co/GaAs ferromagnetic semiconductor has been prepared by the ion-implantation method, and the sample surface has been sputter-etched for examining the magnetic and transport properties as a function of the depth. Extraordinary Hall effect increases with depth until 120 nm etching, and the Hall resistance is proportional to the square of resistance, indicating the side-jump mechanism, in the depth region of 10–60 nm. The depth profiles of the saturation magnetization and the conductivity are estimated analytically, and then the Hall coefficient is evaluated as a function of etching depth.