Observation of recorded tracks in Co-Cr media by magnetic force microscopy

Tracks recorded on two Co-Cr layers having coercivities of 15 kA/m and 45 kA/m were investigated by magnetic force microscopy. Different wavelengths were recorded, corresponding to bit lengths between 0.125 and 0.5 μm. In the case of the layer with the low coercivity, the bits in a track recorded with a wavelength of 0.5 μm were obscured by the meandering nature of the transitions, something which is not observed for the high coercivity layer. This is consistent with a higher noise level and a lower signal level for the low coercivity layer in recording experiments. A more detailed observation of the tracks in the high layer revealed the presence of subdomains in the recorded bits. The extent to which regular domain patterns (recorded bits) or more detailed magnetic structures can be observed depends on the size of the magnetic tip and the distance between tip and layer. The observed width of the intrinsic domains in these layers agrees well with calculated values