Magnonics: Spin Waves on the Nanoscale

Abstract

Magnetic nanostructures have long been in the focus of intense research in the magnetic storage industry. For data storage the nonvolatility of magnetic states is of utmost relevance. As information technology generates the need for higher and higher data‐transfer rates, research efforts have moved to understand magnetization dynamics. Here, spin waves and their particle‐like analog, magnons, are increasingly attracting interest. High‐quality nanopatterned magnetic media now offer new ways to transmit and process information without moving electrical charges. This new functionality is enabled by spin waves. They are confined by novel functioning principles, which render them especially suitable to operate at the nanoscale. Magnonic crystals are expected to provide full control of spin waves, similarly to what photonic crystals already do for light. Combined with nonvolatility, multifunctional metamaterials might be formed. We report recent advances in this rapidly increasing research field called magnonics.

Direct dynamic imaging of non-adiabatic spin torque effects

“…For example, the accuracy of recent measurements of static vortex shape and core trajectories in spin torque nano-oscillators 24 can be re-examined with the improved resolution of electron microscopy. Also, with advances in sensitivity, the timeaveraged and high-resolution imaging technique can be extended to image spin wave patterns in magnonic crystals 25 , as well as realspace studies of nodal patterns in arrays of phase-locked spin torque nano-oscillators 26 acting as spin-wave point sources. Such capabilities will be of great value in developing these promising technologies for computation and communications applications.…”

A micromagnetic study of the reversal mechanism in permalloy antidot arrays

“…[30][31][32] Other important efforts have been made to investigate dynamic properties, focusing on ferromagnetic resonance phenomena and spin-wave propagation for possible application in magnetic logic devices. [33][34][35][36][37][38][39][40][41] A fundamental support to understand the complex magnetic behavior of antidot arrays has been found in micromagnetic simulations based on the solution of the LandauLifshitz equation. 42,43 To limit the computational time and the memory requirements, the micromagnetic simulations have often been performed by introducing periodic boundary conditions on the edges of the unit cell that defines the spatial period.…”

Magnetic antidot to dot crossover in Co and Py nanopatterned thin films

“…The control of the magnetic properties of ferromagnetic thin films is an important topic for both the fundamental understanding of low-dimensional magnetism and a broad range of applications, such as magnetic recording media [1], sensors [2], and magnonic devices [3,4]. A strong dependence of the magnetization reversal mechanisms on the microstructure and the presence of defects makes magnetic properties hardly controllable.…”