Interaction effects in magnetic nanostructures

Abstract

The magnetic properties and propagation of electromagnetic waves in magnetic nanoparticle systems strongly depend on the interactions between the nanosize elements having finite separation. Several aspects of the role of the dipolar and exchange interactions are reviewed on model periodic 2D and 3D magnetic nanostructures. Experiments and theory expose the critical role of proper calculation of dipole fields and statistical distributions. The control and optimization of interactions is illustrated on an example of hexagonal Permalloy ellipse arrays. The competing particle and array anisotropy, leading to a spin reorientation phase transition in Permalloy nanowires, is demonstrated. Finally, the effect of the system configuration on the interactions with electromagnetic waves is shown for ferrite and metal magnetic nanosphere arrays, demonstrating specific nanomagnetic effects, as a transition from insulator to metal, and early onset of nonlinearities.

Formation of the band spectrum of spin waves in 1D magnonic crystals with different types of interfacial boundary conditions

“…Magnonic crystals therefore represent a class of metamaterials, often referred to as "magnonic metamaterials", [73][74][75][76][77][78] which also includes systems that are not periodic, such as magnonic quasi-crystals [79][80][81][82][83][84][85] and (when considered from the point of view of their dynamic properties) magnetic composites. [86][87][88][89][90][91][92][93] The nature of the interlayer magnetization boundary conditions has crucial consequences for the scattering of spin waves from interfaces between regions with different magnetic properties. [94][95][96][97][98][99][100][101][102][103][104][105][106] It is therefore of essential importance for magnonics and magnonic technology, in which spin waves are studied and exploited.…”

Arrays of elliptical Fe(001) nanoparticles: Magnetization reversal, dipolar interactions, and effects of finite array sizes

“…The properties of the particles were reviewed by Guslienko [11], and their sensitivity to dipolar interactions was studied for different array configurations, e.g., by Novosad et al [12]. Also arrays with elliptical permalloy particles were studied, but to a lesser extent; see, e.g., the work by Wang et al [13], Pardavi-Horvath [14], and references therein.…”

Spin waves and electromagnetic waves in magnetic nanowires

“…In this situation for strongly coupled wires the magnetic easy axis reorients from parallel to perpendicular to the wire axis (Pardavi-Horvath et al, 2008b;Tartakovskaya, 2010;Pardavi-Horvath, 2014). It is assumed that H A ¼ 0 for polycrystalline materials.…”

“…For a strongly interacting system the shape of the sample, and not of the wires, will determine the internal field (Pardavi-Horvath et al, 2008b;Pardavi-Horvath, 2014). The internal field, H i , of the system changes, and for particles on a periodic lattice of saturated particles, H i and H r will change by the interaction field.…”