This book treats the various aspects of noise from magnetic recording media and the impact on system performance. Several authors present discussions of: materials and processes used to fabricate media for computer data storage, theoretical aspects of noise and micromagnetic behavior, experimental methods and characterization, and system analysis. In the past decade thin film recording media have largely displaced particlate media in rigid disk recording systems. During the same period of time the field has evolved from the prevalent belief that thin film media were virtually noiseless to a detailed understanding of the origin and the manifestation of noise in these new media. This understanding has lead to the ability to make the very low noise media needed in present applications. The present state of understanding of both particulate and thin film media is summarized.

This is the first book about functional nanostructures. Nanocrystalline materials exhibit outstanding properties and represent a new class of structural materials having a wide range of applications. In particular, there is considerable interest in developing nanocrystalline materials to be used as functional materials in aerospace applications, automotive industry, wear applications, etc. Future progress in these high technological applications of nanocrystalline materials depends on development of new methods of their fabrication and understanding of the underlying nano-scale and interface effects causing their unique mechanical properties.

We have pursued two lines of research during the first year and a half of this work. In the main portion of the project we have performed fundamental investigations of the microstructure and crystallographic texture of Co based alloys deposited on Cr underlayers. This has included atomic resolution electron microscopy of the cross-sections of CoNiCr on Cr thin films, as well as studies of the microstructures and properties of magnetic thin films produced with interlayers of Cr. The other portion of our work has centered on understanding the crystallography and crystal structure of CoSm/Cr thin films. These CoSm films have the potential of being utilized as high density media, but their structure is not yet understood.