Anomalous coercivity on CoCr-films: Surface and Bulk Measurements

The major and minor loops of RF sputtered CoCr films in the thickness range of 20 - 1000 nm and the concentration range of 19-24 at. % Cr were measured by Kerr tracer and VSM. Differences between bulk and surface magnetic data are most likely due to a thickness-dependent surface chemical composition. The maximum anomality of the minor loop coercivity, which depends strongly on the film thickness, appears to be larger at the surface than in the bulk. The anomalous coercivity of the minor loop which is related to a domain pattern change could be caused by repulsive forces between domain walls. It can be concluded that study of the minor loop coercivities is an interesting research tool for micromagnetic behavour.