Magnetic properties of ultrathin Fe3O4 on GaAs(100)

Abstract

The evolution of magnetic phase and anisotropy of epitaxial half-metallic Fe3O4 ultrathin films on GaAs(100) has been studied using magneto-optical Kerr effect (MOKE) measurements. While no magnetic signal was detected below 1 nm, the film shows a superparamagnetic response at a thickness of around 1.6 nm. Ferromagnetic MOKE loops with strong in-plane anisotropies were observed above 2.0 nm. The films show a magnetic uniaxial anisotropy in a thickness range of about 2.0–6.0 nm with the easy axis along the [01̄1] direction.