On the Relationship between Magnetic Viscosity and Coercivity of Perpendicular Media

The dependent and dc-demagnetization measurements were performed on two types of perpendicular thin film media, Co-Cr and Fe-alumite. From these the parameters for magnetic viscosity and irreversible susceptibility were derived. Their ratio, resulting in the fluctuation field, is shown to relate logarithmically to the coereivity. This so-called “Barbier plot for perpendicular media” is found to exhibit a slope of approximately one and a half instead of one, as is found for in-plane media. The activation volumes were also derived and related logarithmically to the coercivity. Here a slope of approximately minus one and a half was found, instead of minus 0.73 as is found for in-plane media

Investigation on Co-Cr micro-strips for VBLM

Hard magnetic strips can be used for bit stabilization in a VBLM. For this stabilization the magnetic strayfield of the strips induce potential wells for the bits. However, by dimensioning a material into strips the magnetic properties and therefore the potential wells change. In this paper the relation between magnetic properties and shape of Co-Cr micro-strips is investigated. Furthermore the influence of both magnetic properties and shape of the strips on the magnetic strayfield is simulated

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