Noise studies of spatial chaos in magnetic recording media

The analysis of noise in magnetic recording tapes has been approached from a fresh perspective. Magnetic microstructure, which is dependent on physical microstructure, applied field and magnetic history, is treated as a spatial dynamical system. An introduction to nonlinear spatial dynamics is presented with a particular emphasis on chaos. These principles are applied to noise time series generated by moving a tape, bearing a fixed magnetic microstructure, past a read head. Evidence is provided that noise from the media is deterministic in origin, being chaotic rather than random. A qualitative difference in dynamical behaviour is observed between oriented and unoriented tape systems. In addition, it is shown that one of the dynamical quantifiers we employ, the pointwise fractal dimension, varies systematically as a function of remanent state as the tapes are taken through a de demagnetisation process. The fractal dimension is interpreted in terms of the magnetic microstructure. In conclusion, the nature of the dynamics underlying noise in magnetic recording media is considered.