MAGNETIZATION PROCESS IN A CLASSICAL SYSTEM OF PREISACH-TYPE PARTICLES

The magnetization process of a regular two-dimensional array of small individual, strongly uniaxial magnetic garnet particles, groups of par ticles and major loop properties of a ''macroscopic'' sample has been investigated experimentally in an optical magnetometer. These particle s correspond to the assumptions of a simple Preisach model. The switch ing mode is coherent rotation. Each particle has a square hysteresis l oop, with no reversible or apparent reversible component. Requirements of wiping-out and congruency properties are satisfied. From measureme nts of the up- and down switching fields on individual particles, the major loop can be reconstructed, and it is shown to be in nearly exact correspondence with the measured one. The transition from individual to collective behavior is smooth and the properties of a system consis ting of 100 particles correspond to the major loop behavior. The inter action field for an assembly of 25 particles was calculated numericall y. The switching sequence and the magnetization curve for the 25 parti cles assembly was derived from the calculated interaction fields and f ound to be in a very good agreement with the measured values.