Spin waves in finite chain of dipolarly coupled ferromagnetic pillars

Highlights: • Properties of finite arrays of magnetic pillars depend on the total number of pillars. • Solutions were found for different configurations of the magnetization in chains. • Edge modes are present in the finite chains of magnetic pillars. • Resonance properties of the chain depend on the position of the defect in the chain. The features of spin waves propagation in an array of ferromagnetic pillars are considered in a theoretical approach that takes into account dipole-dipole interaction between them. Calculations for a finite linear chain of pillars in macrospin approximation shows that such system has several resonant frequencies, which depend upon the edge effects and the geometrical parameters of the structure. Various configurations of the magnetization of the pillars are considered and it is shown that the frequency characteristics are differ in the cases of (i) unidirectional magnetization of the pillars (ferromagnetic configuration), (ii) opposite directions of the magnetization (antiferromagnetic configuration) and (iii) unidirectional magnetization with singular defects.