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 DeltaM from the Wohlfarth equation for non interacting particles which requires the measurement of the remanence curves. The other is an easier procedure which consists in the determination of the deviation DeltaM* from an equation based on the initial magnetization curve and the hysteresis loop. For systems of oriented uniaxial anisotropy particles is generally DeltaM = 2 DeltaM*, while for systems of oriented multiaxial particles or of random oriented particles is DeltaM = 4 DeltaM*. The advantage of the second method is its applicability on systems where the initial magnetization curve and the hysteresis loop must be corrected by the demagnetizing field as for CoCr films magnetized perpendicularly to the film plane