Electric-Field Control of Magnetism in Ferromagnetic Semiconductors

Electric field effect enables us to control charge carrier accumulation/depletion and is an indispensable technology in semiconductor electronics. Quite recently, the electric field induced ferromagnetism at room temperature in a ferromagnetic oxide semiconductor was reported. In this chapter, current status about the electric field effect of ferromagnetic semiconductors is described. The magnetization reversal by current injection is expected to be performed with much smaller current density when the magnetization amplitude is reduced by electric field effect. In general, magnetic circular dichroism (MCD) of ferromagnetic semiconductor is proportional to the energy derivative of the absorption spectrum, so that MCD signal is sufficiently large around at the absorption edge, and its magnetic field dependence reflects that of the magnetization. One of the important properties of ferromagnetic semiconductor is the capability of electrical control of the ferromagnetism, as a result of the carrier-mediated mechanism.