A comparison between different methods for evaluating the particle interactions in magnetic recording systems

Two different methods for the determination of the magnetic interparticle interactions in recording systems are compared. The first one is that based on the evaluation of the deviation Δm from the Wohlfarth equation for noninteracting particles which requires the measurement of the remanence curves. The other is an easier procedure which consists in the determination of the deviation Δm* from an equation based on the initial magnetization curve and the hysteresis loop. For systems of oriented uniaxial anisotropy particles the solution is generally Δm≅2Δm*, while for systems of oriented multiaxial particles or for random oriented particles it is Δm≅4Δm*. The advantage of the second method is its applicability to systems where the initial curve and the hysteresis loop must be corrected by the demagnetizing field as for CoCr films magnetized perpendicularly to the film plane