Microstructure of Longitudinal Media

In this chapter we give an overview of the effects of various microstructural features on the resulting magnetic properties of magnetic thin films. The role of microstructure on certain properties of materials has a long history of investigation, starting in the discipline of physical metallurgy where the role of microstructure on properties was investigated in great detail [1]. It became clear that some properties were relatively insensitive to changes in microstructure and others were strongly sensitive to changes in microstructure. The former were called intrinsic properties or sometimes primary properties, since they were intrinsic to the material. The latter were called extrinsic properties or secondary properties, since they were dependent on features that were not inherent to the material [2]. With the advent of the discipline of materials science the role of material processing was included in the way extrinsic properties were understood. Changing the method of producing a material often changed some of the resulting physical properties of the material. This change was shown in many cases to be mediated through the change in microstructure of the material. This lead to the so called materials science paradigm: processing determines microstructure which in turn determines the extrinsic properties of a material.