Fast switching and coercivity in thin-film recording media

The effects of finite-switching rates of media on measured coercivities are studied using two methods. The first starts from expressions for the switc hing times of magnetic media and goes on to derive simple expressions for t he coercivities of media subjected to various applied field wave forms. The second uses a well-developed numerical micromagnetic model to investigate both the switching times and coercivities. The variations of coercivity wit h frequency derived using the two methods show similar results. (C) 2001 Am erican Institute of Physics.