Growth of nanosized MnAs/Si(111) magnetoelectronic heterostructures and their magnetooptical study

Thin (6–12 nm) epitaxial MnAs films were MBE-grown on Si(111) substrates under different technological conditions. The films feature essentially different surface morphology. This manifests itself in the formation, on the silicon surface, of hexagonal-shaped crystallites, whose dimensions vary depending on the growth conditions. The volume and surface magnetic properties of the films were studied using the magnetooptical Kerr effect and optical second harmonic generation. The Kerr effect was found to scale linearly with the effective thickness of the magnetic layer. The thickness of the magnetically disordered transition layer formed near the interface with the substrate was estimated. The surface and volume hysteresis properties of the films were found to be different. A contribution to the second-harmonic intensity was observed which is an odd function of magnetization. This effect originates from the interference of the magnetic and nonmagnetic contributions to the nonlinear polarization.