Grain structure and magnetic clustering in SiO2 added CoNiPt granular films

Abstract
Grain structure and its relation to the magnetic properties in SiO2 added CoNiPt granular films have been studied, with the SiO2 content varied from 0 to 8 mol %. With SiO2 more than 4 mol %, significant grain boundaries with a width of a few nm are formed by the segregated SiO2 . The average grain size in the film plane decreases from 16 to 9 nm with the SiO2 increased up to 8 mol %. The media noise significantly decreases with increasing SiO2 and remanent magnetized domains observed by magnetic force microscopy (MFM) also become finer. With 8 mol % SiO2 , MFM shows that weak magnetic clustering spreads over the grains, with a diameter of about 100 nm. This clustering indicates the collaborative behavior of the magnetization between grains is responsible both for the steep magnetization reversal as well as the slight increase in the media noise as the recording density is increased.