Magnetism of ultrathin FeCo (001) films on GaAs(001).

Epitaxial Fe[sub 34]Co[sub 66] films in a thickness range from 3 to 100 monolayers (MLs) were grown by molecular beam epitaxy on GaAs(001) at room temperature. The growth was characterized by reflection high energy electron diffraction and x-ray diffraction. The magnetic properties were investigated by alternating gradient magnetometry magneto-optic Kerr effect, and superconducting quantum interference device magnetometry. The films show a strong interface-induced uniaxial in-plane anisotropy with the easy axis along [110]. In addition, the fourfold anisotropy coefficient changes sign around 6 ML i.e., the easy axis of the fourfold anisotropy switches from <110> to <100> with decreasing thickness. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]