Magnetization of superparamagnets in the state of mechanical anisotropy

Abstract

The internal energy of magnetic anisotropy in some particles dominates over the thermal energy, even at room temperature. The existence of strong magnetic anisotropy of nanoparticles can significantly affect the process of magnetization of superparamagnets. However, if the axes of magnetic anisotropy of nanoparticles are randomly oriented, then their presence does not affect the process of magnetization, which occurs according to the classical Langevin theory. However, if the axes of nanoparticles are polarized (mechanical anisotropy), then the magnetization curve of a superparamagnet under the conditions of mechanical anisotropy lies between the Langevin curve and the curve of hyperbolic tangent and with increasing anisotropy moves progressively farther from the Langevin curve and approaches the curve of hyperbolic tangent. It has also been shown that, in the case of powder superparamagnets, the presence of mechanical anisotropy leads to significant changes in the Curie constant.