Effect of elastic and plastic deformations on the remanent magnetization of an ensemble of nanoparticles

Abstract

A theoretical investigation of the effect of mechanical stresses on the remanent magnetization has been performed in terms of the model of single-domain noninteracting nanoparticles. Relationships have been obtained which define two main types of remanence in the entire range of stresses. In the low-field approximation, the magnetization of the first type, whose mechanism of formation is similar to that of the normal remanence, is quadratic in both the magnetic field and stresses and only slightly changes with increasing stresses. Depending on the relationship between the magnetostriction constants, this magnetization can both increase and decrease with increasing stresses. The magnetization of the second type, which arises as a result of a nonmonotonic behavior of the critical fields of nanoparticles depending on mechanical stresses, is proportional to the magnetic field and mechanical stresses. It has been shown that the longitudinal remanence arising in the field of stresses parallel to the magnetic field is always greater than the transverse remanence. The behavior of the remanence with increasing mechanical stresses depends substantially on whether this magnetization is formed in a loaded state or in a state unloaded after plastic deformation. In the range of deformations where the anisotropy of the applied stresses is less than the magnetocrystalline anisotropy, the plastic tension should lead to a decrease in the magnetization as compared to that arising in the plastically undeformed state. Plastic compression can lead to both an increase and a decrease in the remanence.