Ferrofluid studies of recorded data and defect identification in small high-performance rigid discs

In this work, a newly developed ferrofluid was used for studying recorded data patterns on high-performance rigid discs where densities exceed 10 000 frpi. It has been found that ferrofluids must exhibit certain properties to be useful in this application. Fluid properties such as particle size distribution, concentration and stability are described as they relate to optical (microscopic) resolution of the magnetic pattern. The application of this new water based ferrofluid for single-bit defect detection is also discussed in conjunction with a novel method which was developed for this use.