Continuum Model of Free Induction Decay in Diluted Magnetic Composite

The study presents an analysis of free induction decay (FID) in the diluted magnetic composite using the model of spin waves in continuous media. It takes into account the dipole–dipole interaction of the bulk lattice atoms and between them and ferromagnetic dopant ions, and also the indirect exchange interaction of the dopants. A dispersion relation of the magnetic waves is evaluated from the magnetization evolution equation. There are two spectrum branches of spin waves. Their basic frequencies are determined by the gyromagnetic ratio and interaction parameters of the dopant ions and bulk lattice atoms, and by the dopant concentration. The FID asymptotic behaviour is evaluated.