Investigation of L10 FePt-based soft/hard composite bit-patterned media by micromagnetic simulation**Project supported by the National Natural Science Foundation of China (Grant Nos. 51171086 and 61272076) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 61003041).

Abstract

The soft/hard composite patterned media have potential to be the next generation of magnetic recording, but the composing modes of soft and hard materials have not been investigated systematically. L10 FePt-based soft/hard composite patterned media with an anisotropic constant distribution are studied by micromagnetic simulation. Square arrays and hexagonal arrays with various pitch sizes are simulated for two composing types: the soft layer that encloses the hard dots and the soft layer that covers the whole surface. It is found that the soft material can reduce the switching fields of bits effectively for all models. Compared with the first type, the second type of models possess low switching fields, narrow switching field distributions, and high gain factors due to the introduction of inter-bit exchange coupling. Furthermore, the readout waveforms of the second type are not deteriorated by the inter-bit soft layers. Since the recording density of hexagonal arrays are higher than that of square arrays with the same center-to-center distances, the readout waveforms of hexagonal arrays are a little worse, although other simulation results are similar for these two arrays.