Synthetic antiferromagnet for hard layer of exchange coupled composite media

It has been shown that exchange coupled composite (ECC) media exhibit a superior thermal stability to switching field ratio compared to conventional perpendicular media. However, optimal media designs have employed a low magnetization hard layer. A more physically achievable design may consist of replacing the hard layer with a synthetic antiferromagnet consisting of two ferromagnetic hard layers coupled by an antiferromagnetic exchange interaction. This approach is shown to decrease the switching field and increases the thermal stability ratio when compared to ECC media with a single hard layer.