Local Ferromagnetic Resonance Imaging with Magnetic Resonance Force Microscopy

Abstract

We report nanoscale scanned probe ferromagnetic resonance force microscopy (FMRFM) imaging of individual ferromagnetic microstructures. This reveals the mechanism for high spatial resolution in FMRFM imaging: the strongly inhomogeneous local magnetic field of the cantilever mounted micromagnetic probe magnet used in FMRFM enables selective, local excitation of ferromagnetic resonance (FMR). This approach, demonstrated here in individual permalloy disks, is straightforwardly extended to excitation of localized FMR modes, and hence imaging in extended films.

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

“…We performed micromagnetic modeling [12,[25][26][27] Fig. 3(b), reduced by 50 G to account for the Oersted field and heating from I DC (determined by the shift of the quasi-uniform mode).…”

“…3(c). To identify the localized modes resonances, we performed micromagnetic modeling [12,[25][26][27] at θ = 70 ○ , using a value of 4πM eff = 8.7 kG, determined from the in-situ Py/Pt film (both at I DC = 0). For a Py thickness of 5 nm, the four lowest-energy localized modes are three width modes (n = 1, 2, 3) [13] and one higher-order length mode (n = 1, m = 2).…”

Ferromagnetic Resonance Measurement Using a Novel Short Circuited Coaxial Probe Technique

“…Resonant structures (coaxial, dielectric, and cavity resonators) are most commonly used to characterize materials at microwave frequencies. A few techniques based on scanning probe microscopy (SPM) for imaging spatial distributions of magnetic response in a range of radio frequency (RF), such as electron paramagnetic resonance and FMR, have been developed [4][5][6][7]. FMR signals on a polycrystalline YIG disk has been observed using the openended coaxial electric probe by Toshu et.al [8].…”

Imaging interfaces defined by abruptly varying internal magnetic fields by means of scanned nanoscale spin wave modes

“…Ferromagnetic Resonance Force Microscopy (FMRFM) exploits the spatially inhomogeneous magnetic field generated by a micromagnetic probe to spatially confine spin wave modes enabling microscopic imaging of the internal magnetic fields [13,14] as well as local excitation of spin wave in order to probe local spin dynamics and transport in buried and exposed magnetic nanostructures [15][16][17].…”