The spatial structure of media noise

The spatial structure of dc and transition noise in perpendicular and longitudinal recording media is studied. Experimental techniques for local dc noise and transition noise analysis are described. It is demonstrated that the dc and transition noise is deterministic and repeatable at given medium location. The transition noise is correlated with the dc noise; the local fluctuations of the dc saturated magnetization are becoming enhanced when a transition is written at this location. This enhanced local dc noise is explained by local medium demagnetization which is strongest at the transition, it determines the transition noise magnitude.