Correlations between magnetic switching volume and magnetic and nanostructural properties of CoSm//Cr films (abstract)

CoSm films with a Cr underlayer (CoSm//Cr) are promising as future high density recording media.1 It was pointed out that the grain size in media affects the media noise and thermal stability significantly. However, if small grains are exchange coupled to form larger “magnetic grains,” the size of these magnetic clusters will be important in noise considerations. Our previous works23 indicated that for CoSm film with Cr underlayer the magnetic grain size is much larger than the 50 A nanocrystallites and is about the same size as the Cr grain of ∼240 A in dimension. In the present work, we report our systematic studies of magnetic switching volume and its correlation with magnetic and nanostructural properties for CoSm films. Switching volumes V* were measured with the “field sweep-rate dependence of coercivity Hc,” interactions among the magnetic grains were estimated with the so-called ΔM method, and the nanostructures were investigated with atomic force microscopy and transmission electron microscopy. T...