Magnetic films epitaxially grown on semiconductors

Future 'magneto-electronics' exploiting the spin of the electron in addition to its charge will require the injection of spin-polarized electrons from a ferromagnetic metal into a semiconductor. To this purpose an attempt has been made in the present study to avoid the formation of a non-magnetic interface phase or 'magnetically dead layers' which have been found in the past in Fe films epitaxially grown on GaAs(001). Fe(001) films were grown by molecular beam epitaxy and magnetron sputtering on As depleted GaAs(001) surfaces held at room temperature. Very good epitaxial growth is achieved by both deposition methods. MBE grown ultrathin films show an enhanced ground state net magnetization and the full bulk magnetic moments at the Fe/GaAs interface in contrast to previous reports. This might be an important step towards semiconductor devices using spin polarized electron transport. The in-plane magnetic anisotropy of the films generally consists of a fourfold and a uniaxial term. At 7 monolayer thickness only a strong uniaxial contribution is observed which is supposed to result from the intrinsic anisotropy of the dangling bonds at the GaAs(001)surface. This could also be a useful property for future memory or switching applications.