Measurements of the remanent magnetization of some individual magnetic particles near the single-domain size

Results of remanence measurements on individual small particles are reported. The measurements were carried out on a very fine quartz fibre torsion balance, the quartz suspensions being of the order of 0•5 μ in diameter. The specimens had linear dimensions of the order of 1 μ, which is near the critical size for single-domain behaviour in some of the materials investigated. Evidence of discontinuous jumps in the remanence-field curves was detected, and in some cases a decrease in remanance on increasing the magnetizing field was observed.