Magnetic remanence properties of particulate recording media: comparison of barium ferrite with acicular materials

The magnetic remanence properties of barium ferrite particulate media were studied and compared with those of acicular particulate materials to understand better the differences in recording properties. The loss of remanence after the application and removal of an applied magnetic field was measured for fields opposite and transverse to the direction of initial magnetization. The loss of remanence after application of a reverse field gives information about the distribution of switching fields; this distribution is narrower in barium ferrite than in acicular materials. The loss of remanence after the application of transverse fields gives information about the magnetic anisotropy; barium ferrite is much more resistant to demagnetization by transverse fields than are acicular materials, but only in oriented media. All results are analyzed in terms of their dependence on relevant magnetic squareness parameters to account for the differing degrees of particle orientation in the samples and thus to observer fundamental differences in material properties