Magnetization fluctuations in uniformly magnetized thin-film recording media

The noise power spectrum of uniformly magnetized media is measured. The measured spectra are corrected for playback effects (gap loss, spacing loss, head differentiation, and amplifier gain) to yield the spectrum of the medium magnetization fluctuations. The resulting spectral shape approximately fits a simple Lorentzian form. Fluctuation correlation length and variance are easily determined for all states of medium magnetization. Noise power data are compared to the results of in-situ remanence measurements. DC current applied to the recording head produced the uniform magnetization states for which the noise was analyzed. The remanent magnetization corresponding to each current was determined by recording long-wavelength square waves utilizing the same current amplitude that produced the uniformly magnetized state