Origin of the magnetization reversal of an Fe thin film on Si(111)

The magnetic behavior of a 60-Å Fe film grown on Si (111) is reported and discussed. Scanning tunneling microcopy images showed Fe stripes along one of the (110) directions in the (111) plane, which favors easy magnetization axis parallel to the stripes. Inverted in-plane hysteresis loops and loops with unusual local peaks were measured and interpreted. A phenomenological model was proposed to interpret the magnetization data and an excellent concordance between the experimental and the calculated curves was obtained. The peculiarities in the magnetization curves are directly related to the very small misorientation of the sample’s surface from the (111) plane, and to competing anisotropies. The model calculations showed that the magnetization leaves the sample’s plane for small fields, forming an obtuse angle with the field for some configurations, thus resulting in negative remanence, which was confirmed by the nonzero values of the normal to the plane magnetization component from the magneto-optic Kerr effect polarimetry measurements