Exchange coupling strength in synthetic ferrimagnetic media

The antiferromagnetic exchange coupling strength (H-ex) between two CoCrPtB magnetic layers in bilayer synthetic ferrimagnetic media (SFM) is investig ated. H-ex is found to be inversely proportional to the thickness and magne tization of the initial magnetic layer (L1). H-ex also shows a decrease wit h increasing temperature. An exchange coupling strength of J approximate to 0.05 erg/cm(2) was obtained from H-ex. For further improvement of thermal stability at higher recording densities, the thickness or magnetic anisotro py of L1 may be increased. On the other hand, for an effective SFM, the coe rcivity of L1 must be lower than H-ex. Therefore, a large H-ex is critical for better thermal stabilization.