Sixth-order contribution to the cubic anisotropy in Fe(1 1 1) thin films on Si(1 1 1)

Combined transverse biased initial inverse susceptibility and torque measurements were performed on thin Fe(1 1 1) films epitaxially grown on Si(1 1 1), using a conventional magneto-optical Kerr effect magnetometer. This new method, called TBIIST, is a well suitable and sensitive technique for the study of magnetic anisotropies and in particular provides an accurate value of the anisotropy field strength in the sample and a precise determination of the anisotropy axes. For this purpose a 160 monolayer Fe film grown on Si(1 1 1) at normal incidence was investigated. A very small sixth-order contribution to the cubic anisotropy is readily detected, as expected for a Fe(1 1 1) film, corresponding to anisotropy fields as low as a few tenths of an Oersted.