Evaluation of 45° method in characterizing the anisotropy of the perpendicular media

The 45° method has become increasingly popular in characterizing the anisotropy energy of perpendicular recording media. However, this method had only been evaluated under the framework of single-domain particle model. In this paper, we evaluate the 45° method using both the Monte-Carlo and LLG simulation by taking into account the grain structure and the inter-granular exchange interactions. The simulations show that multiple domains form during a 45° measurement, even for samples with squareness close to 1. Domain formation becomes less of a problem if a large external field is applied (∼Hk). These modeling results impose question marks on the advantages for the 45° method and suggest that this method should be applied with caution.