Temperature dependence of the coercive field in single-domain particle systems

The magnetic properties of Cu₉₇Co₃ and Cu₉₀Co₁₀ granular alloys were measured over a wide temperature range (2--3000.3em0exK). The measurements show an unusual temperature dependence of the coercive field. A generalized model is proposed and explains well the experimental behavior over a wide temperature range. The coexistence of blocked and unblocked particles for a given temperature raises difficulties that are solved here by introducing a temperature dependent blocking temperature. An empirical factor gamma (γ) arises from the model and is directly related to the particle interactions. The proposed generalized model describes well the experimental results and can be applied to other single-domain particle system.