Micromagnetic studies on exchange coupled composite recording media

The exchange between the hard and soft layer in the exchange coupled composite (ECC) medium is crucial for the recording performance. An accurate micromagnetic model is built for Co-TiO2 (4 nm)/Pt(delta=0-2.8 nm)/CoPt-TiO2 (16 nm) ECC media, based on the microstructure, to investigate the magnetic parameters such as the exchange constant A*(3) between the soft/hard layer. In the M-H loops of CoPt-TiO2(16 nm) hard layer, the perpendicular coercivity is 6.1 kOe and the squareness S is 0.98. In ECC media, the thickness delta of interlayer Pt has comprehensive effects on magnetic properties: the coercivity and squareness change little when we just vary A*(3) or delta; A*(3) equals the intragrain exchange constant A*(1) when delta is thinner than grain boundary (<= 2 nm); and A*(3) decreases from the intergrain exchange constant A* (2) to 0 when delta increases from 2.2 to 2.8 nm. The simulation results agree well with experiments. (C) 2012 American Institute of Physics. [doi:10.1063/1.3679450]