On the Statistical Character of Magnetic Properties of Single-Crystal Particles in Highly Anisotropic Ferromagnetics

Abstract

Magnetization reversal processes of single-crystal particles in SmCo5 and GdCo5 alloys were studied by observing the domain structure by means of Kerr-magnetooptic effect. The influence of different factors on the coercivity Hc and stability of the single-domain particle state was investigated. It is shown that when the number of observed particles is large and the measurements are performed repeatedly some general regularities can be found such as a rise in Hc with an increase in amplitude of the magnetizing field to 17 kOe or with the decrease in particle size from 300 to about 10 μm, and a fall in Hc with increasing temperature from —130 to +320 °C. It is found that a rise in Hc of particles at room temperature results in an increase in their single-domain temperature stability. The theoretical dependence of Hc on the magnetizing field is calculated on the assumption of pinning in displacement of residual domain boundaries on structure defect clusters. The statistical character of observed regularities in changes of magnetic properties of particles is emphasized.