Spectrum and reflection of spin waves in magnonic crystals with different interface profiles

Abstract

Using the transfer-matrix method, we have developed a theory of exchange spin waves in a thin cylindrical magnonic crystal ͑periodically layered all-ferromagnetic nanowire͒ with diffuse interfaces. The magnonic spectrum and the frequency dependence of the reflection coefficient of spin waves from a junction between a homogeneous magnetic nanowire and a magnonic crystal have been calculated and compared. Diffuse interfaces with linear and sinusoidal profiles of variation in the uniaxial anisotropy value have been considered, also allowing for asymmetry in the relative thicknesses of either main layers, or interfaces, or both. We have found that, although the thickness and profile of interfaces have a significant effect on the size and position of the magnonic band gaps, the smoothing of interfaces does not lead to disappearance of the band gaps. At the same time, the profiles and relative thicknesses of interfaces might provide additional means by which to design magnonic crystals with a desired magnonic spectrum.

Magnetization boundary conditions at a ferromagnetic interface of finite thickness

“…11 Both cases would require a more complex interface modeling that would account for the interface regions on equal grounds with the semi-infinite materials A and B. [60][61][62][63][64][65]95,96 The generalized Barnaś-Mills boundary conditions proposed in this paper are not limited to linear spin wave dynamics but could equally be applied to the theory of nonlinear spin waves. 97,98 Moreover, although the discussion above has been limited to the exchange spin waves, the boundary conditions could also be applied in the theory of magnetostatic, dipole-exchange, or even retarded spin waves.…”

An effect of the curvature induced anisotropy on the spectrum of spin waves in a curved magnetic nanowire

“…[7][8][9][10][11] Recently there is a large number of works devoted to the study of one-and two-dimensional planar magnon crystals formed by periodic structuring of monolayer magnetic films, most often yttrium iron garnet 12,13 or transition metals. [14][15][16] However, since in the magnon devices the topology is essential, it is necessary to study properties of connections between different parts of structural elements of magnonic devices and metamaterials.…”

“…11 A spiral magnetic nanowire with a periodic modulation of the pitch Since it is possible to create low-dimensional systems with a complex geometric shape, interesting is the problem of propagation of SWs in a magnetic nanowire, curled into the shape of a spiral with the modulated pitch.…”

Phase transition in ising magnetic superlattice nanowires: Molecular field theory approach

“…The interesting phenomena and practical benefits discovered in the magnetic materials with magnetic properties modulated in the nanometer scale have led to considerable attention [1][2][3]. In the recent past many experimental and theoretical research have been focused on the properties of magnetic systems in the nanometer scale [4][5][6].…”