Fanning Mode in a Perpendicular Magnetic Film

Abstract

A fanning mode in a columnar-structure film with perpendicular magnetization is studied on the assumption that the film is a two-dimensional array of prisms each of which consists of three identical single-domain grains. From the energy density, the nucleation fields Hj'm for the fanning model and H/w for the coherent-rotation mode are calculated. It is found that the difference between HJan and H/w is about 10% of them at the most. Furthermore the fanning mode occurs only for a very small range of the angle between the direction of the applied field and that of the easy axis of the magnetic uniaxial anisotropy normal to the film plane, and the exchange coupling at the granular interface further reduces this range. Therefore the fanning mode need not be taken into account in columnar-structured films used for perpendicular magnetic recording.