Micromagnetic calculation of spin wave propagation for magnetologic devices

Abstract

The propagation of magnetic wave packets in magnetic nanowires was calculated as a function of wire width, field strength, field ramp time, field area size, and geometry of a magnetic nanowire. Spin waves are excited locally by applying a small perturbation in the magnetization in a 20nm wide region. A wave packet is emitted from the input region and travels along the wire with a velocity of 740m∕s. The finite element micromagnetic simulations show that wave packets can be guided along a bent nanostructure without losses due to geometry; amplitude and frequency are exactly the same as in a straight wire with equal distance between excitation point and probe. The wave amplitude was found to decrease with increasing rise time of the excitation field with an upper limit of 100ps. For a Permalloy wire with a thickness of 10nm, the frequency peak changes from 10GHz in a wire with 60nm width to 6GHz in a wire with 140nm width.

How do spin waves pass through a bend?

“…Bance et al reported the transmission of backward-volume (BV) spin-wave packets through a 90° circular bend without losses8; nevertheless they did not identify the mode distribution of these spin waves, which is essential to understand the spin-wave propagation inside the bend. Quite recently, Dvornik et al demonstrated the fact of the BV spin waves to follow a curved waveguide without noticeable losses at the bend7, and thus claimed that the spin waves adapt the bend with their wave vectors parallel to the local magnetization.…”

Magneto–thermo–elastic fields caused by an unsteady longitudinal magnetic field in a conducting nanowire accounting for eddy-current loss

“…(32) into Eq. (18) and using Eqs (33). and(35), the corresponding PDE to u ð2Þ r ðr; sÞ with its initial and boundary conditions separation of variable technique and reminding that u ð2Þ r should be bounded at the revolution axis points of the nanowire, ðsÞJ a n ðb n rÞ;…”

Proposal for a Standard Micromagnetic Problem: Spin Wave Dispersion in a Magnonic Waveguide

“…These are complemented by efforts to compute the magnetization dynamics in various kinds of magnonic crystals and waveguides, of different geometries and made of different materials [5]- [7]. The dispersion relation, ω(k), provides valuable insights into the characteristics of propagating spin waves (SWs), and aids in our pursuit of building functional devices around magnonic waveguides [8]- [10]. Dispersion relations have traditionally been obtained using experimental means, which often means multiple experimental runs and associated costs and delays.…”