Nanoscale Spin Wave Localization Using Ferromagnetic Resonance Force Microscopy

Abstract

We use the dipolar fields from a magnetic cantilever tip to generate localized spin wave precession modes in an in-plane magnetized, thin ferromagnetic film. Multiple resonances from a series of localized modes are detected by ferromagnetic resonance force microscopy and reproduced by micromagnetic models that also reveal highly anisotropic mode profiles. Modeled scans of line defects using the lowest-frequency mode provide resolution predictions of (94.5±1.5) nm in the field direction, and (390±2) nm perpendicular to the field.

Spectroscopy and Imaging of Edge Modes in Permalloy Nanodisks

“…2. In contrast to some of the previous work [33][34][35][36] where the spin waves in the films were localized by the strong tip fields, this tip has a much weaker stay field due to its small size and no tip-localized modes have been observed. The tip is typically lifted 50 nm off of the sample surface.…”

“…This elongated image shape is partly due to the elongated shape of edge mode profiles [ Fig. 1(a)], but additionally, the point response function for the in plane magnetized tip yields images that appear elongated in the same direction [36]. In addition to contrast from the modes of interest, a faint, frequency/field independent background signal with the shape of the disk can be seen in the 2-D images.…”

“…X-ray microscopy based on magnetic circular dichroism also provides dynamic magnetic imaging [18][19][20] with resolution as fine as 25 nm. [18] In parallel, ferromagnetic resonance force microscopy (FMRFM) [21][22][23][24] has been developed and proven to be a useful tool for various areas in magnetic dynamics, such as spin wave dynamics in confined structures [22,[25][26][27][28][29][30], spin-transfer torque device dynamics [31], defect detection in an array [32], and spin wave localization [33][34][35][36]. With spin waves localized by the stray field from the FMRFM tip, a resolution of 200 nm has been reported [33].…”

Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

“…Localized spin wave modes, confined by the strongly inhomogeneous dipole magnetic field of a nearby scanned micromagnet, have been demonstrated in ferromagnetic resonance force microscopy (FMRFM) for both imaging and studies of magnetization dynamics at * hammel@physics.osu.edu the nanoscale [12][13][14]. Using magnetic field-localization to define the eigen-modes of a spin-Hall oscillator offers a new approach to the study of spin-Hall torque physics, and multi-mode interactions.…”

Nonlinear ferromagnetic resonance shift in submicron Permalloy ellipses

“…The spectra are measured using ferromagnetic resonance force microscopy (FMRFM) [14][15][16][17][18][19][20] , which has a number of advantages for these measurements. First, FMRFM has the ability to measure single structures.…”