High-frequency characterization of Permalloy nanosized strips using network analyzer ferromagnetic resonance

Abstract

We report on the dynamic properties of Permalloy nanostrips at gagahertz frequencies. The thickness of the strips is 100 nm, strip width is 300 nm, strip spacing is 1 m, and length is 0.3-100 m; aspect ratios are 1:1, 1:2, 1:3, 1:5, 1:10, and 1:333. The dynamic behavior was studied by network analyzer ferromagnetic resonance ͑FMR͒ using Permalloy strips on a coplanar waveguide in flip-chip geometry. The FMR mode frequencies ͑f r ͒ can be controlled by the aspect ratio as well as by the applied magnetic field ͑H͒. In longer strips ͑1:10 and 1:333͒, the excitation frequencies show a soft mode behavior ͑H eff = 990 Oe͒ when the field is along the hard axis. However, along the easy axis ͑along the strip length͒, f r increases with applied field. At a field of 3 kOe, f r values are almost independent of aspect ratio along the easy axis except for the 1:1 strip. Along the hard axis, the frequencies are strongly dependent upon the aspect ratio. We also observed that the frequency linewidths of the strips are dependent on the aspect ratio.

Switching dynamics of doped CoFeB trilayers and a comparison to the quasistatic approximation

“…The magnitude of this anisotropy is determined by the structure and its strength can strongly influence the resonance frequencies of the system. 43 The frequency linewidth is reduced as the aspect ratio of the nanomagnet increases. 43 Nanomagnets with high structural quality exhibit very narrow ferromagnetic resonance (FMR) linewidths.…”

“…43 The frequency linewidth is reduced as the aspect ratio of the nanomagnet increases. 43 Nanomagnets with high structural quality exhibit very narrow ferromagnetic resonance (FMR) linewidths. 44 The FMR linewidth can be related to the Gilbert damping parameter and the amount of inhomogeneity in the structure.…”

Ferromagnetic resonance in submicron permalloy stripes

“…The array of permalloy (Ni 80 Fe 20 ) rectangular stripes 3000×500×30 nm 3 (the separation between stripe's centers is about 6 μm) were fabricated by electron-beam lithography and lift-off process. At the first stage the 150 nm resist was deposited on Si substrate by centrifuging.…”

“…The microwave frequency was 9.8 GHz. In calculations the microstrip 3000×500×30 nm 3 was discretized into rectangular parallelepipeds with a square base of size δ = 10 nm in the x,y plane and height h = 30 nm. The choice of geometrical dimensions and aspect ratio (the ratio of thickness, width and length) of microstripes was motivated by convenience for the experimental and theoretical study of the eigenmodes of magnetization oscillations.…”

“…In particular, the PPS consisting of ferromagnetic elements with different shape and spatial arrangement are considered as the effective tuned filters for the ultra high frequency (UHF) electromagnetic radiation [3,4]. The ferromagnetic resonance (FMR) and spin wave resonances (SWR) in PPS strongly depend on the internal fields connected with the shape anisotropy, exchange and magnetostatic interaction.…”