Spin Dynamics in Ferromagnetic Resonance for Nano-Sized Magnetic Dot Arrays: Metrology and Insight Into Magnetization Dynamics

Noh, SeungMo; Monma, D.; Miyake, Koji; Doi, M.; Kaneko, Tomoaki; Imamura, Hiroshi; Sahashi, M.

doi:10.1109/tmag.2011.2150741

Cited by 16 publications

(14 citation statements)

References 7 publications

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“…However, in our case, the bias field is not small (it is in the range < < H H H n a n , i.e., it varies from 50 to 450 Oe), the vortex core is essentially off-centered and such a classification scheme is not applicable anymore. The frequencies f res of the spin wave modes observed in our experiments in the off-centered vortex state depend weakly on the bias field H, and the amplitudes of these modes excited by the spatially uniform external ac magnetic field are substantially smaller than the amplitude of the main spatially uniform mode excited in the quasi-uniform ground state of the dot [13,20] (compare also the absorption curves corresponding to the points 4 and 2 in figure 1). The experimental data presented in figures 2(f)-(h) are interpreted as excitation of the lowest dipolar spin wave mode (with no internal nodes along the radial direction) in the vortex-state dot by a uniform in-plane microwave field, which has a maximal in-plane component of the spatially averaged dynamical magnetization.…”

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confidence: 53%

“…To investigate experimentally the microwave absorption in a two-dimensional array of inplane magnetized non-interacting magnetic dots, we used a standard technique of vector network analyzer ferromagnetic resonance (VNA-FMR) [6][7][8][9][10][11][12][13][14], which has been employed previously to investigate the microwave properties of magnetic dot arrays [8,9,[11][12][13][14][15]. The microwave measurements were conducted by the VNA set-up ZVA-8 (Rohde&Schwarz).…”

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confidence: 99%

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Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

et al. 2014

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When the in-plane bias magnetic field acting on a flat circular magnetic dot is smaller than the saturation field, there are two stable competing magnetization configurations of the dot: the vortex and the quasi-uniform (C-state). We measured microwave absorption properties in an array of non-interacting permalloy dots in the frequency range 1-8 GHz when the in-plane bias magnetic field was varied in the region of the dot magnetization state bi-stability. We found that the microwave absorption properties in the vortex and quasi-uniform stable states are substantially different, so that switching between these states in a fixed bias field can be used for the development of reconfigurable microwave magnetic materials.

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confidence: 53%

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confidence: 99%

Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

et al. 2014

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“…Hence, it is expected that the flexible LFO films are reproducible with different OOP crystal orientations to investigate the origin of the bending tuned microwave magnetism in flexible magnetic thin films. Besides, the influence from the demagnetization field can be discussed by tuning the nanostructure of the LFO film, since it was reported that nanostructure could effectively modulate the demagnetization factor of materials . In the former work, (111)‐oriented CoFe 2 O 4 nanopillar arrays have been successfully grown on flexible fluorophlogopite substrates by the physical deposition and wet etching process, which can be further extended to form the LFO nanostructures …”

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confidence: 99%

A Strategy to Modulate the Bending Coupled Microwave Magnetism in Nanoscale Epitaxial Lithium Ferrite for Flexible Spintronic Devices

Shen

Lan

et al. 2018

Advanced Science

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With the development of flexible electronics, the mechanical flexibility of functional materials is becoming one of the most important factors that needs to be considered in materials selection. Recently, flexible epitaxial nanoscale magnetic materials have attracted increasing attention for flexible spintronics. However, the knowledge of the bending coupled dynamic magnetic properties is poor when integrating the materials in flexible devices, which calls for further quantitative analysis. Herein, a series of epitaxial LiFe5O8 (LFO) nanostructures are produced as research models, whose dynamic magnetic properties are characterized by ferromagnetic resonance (FMR) measurements. LFO films with different crystalline orientations are discussed to determine the influence from magnetocrystalline anisotropy. Moreover, LFO nanopillar arrays are grown on flexible substrates to reveal the contribution from the nanoscale morphology. It reveals that the bending tunability of the FMR spectra highly depends on the demagnetization field energy of the sample, which is decided by the magnetism and the shape factor in the nanostructure. Following this result, LFO film with high bending tunability of microwave magnetic properties, and LFO nanopillar arrays with stable properties under bending are obtained. This work shows guiding significances for the design of future flexible tunable/stable microwave magnetic devices.

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“…Furthermore, the frequency separation of the localized mode resonances from their neighbors and the quasi-uniform mode can be systematically tuned by particle size and particle-sample separation; in particular, confinement parameters can be continuously tuned by scanning the separation between a scanned tip and the sample. Finally, field localized modes avoid the potential spurious effects arising from fabrication edge damage [15,16] associated with lithographically defined structures.…”

Section: Introductionmentioning

confidence: 99%

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

Zhang

Manuilov

et al. 2017

Phys. Rev. Applied

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Auto-oscillation of a ferromagnet due to spin-orbit torques in response to a dc current is of wide interest as a flexible mechanism for generating controllable high frequency magnetic dynamics. However, spin wave mode degeneracies and nonlinear magnon-magnon scattering impede coherent precession. Discretization of the spin wave modes can reduce this scattering. Spatial localization of the spin wave modes by the strongly inhomogeneous dipole magnetic field of a nearby spherical micromagnet provides variable spatial confinement, thus offering the option of systematic tunability of magnon spectrum for studying multi-mode interactions. Here we demonstrate that field localization generates a discrete spin wave mode spectrum observable as a series of well-resolved localized modes in the presence of imposed spin currents arising from the spin Hall effect (SHE) in a permalloy/platinum (Py/Pt) microstrip. The observation of linewidth reduction through damping control in this micromagnetically engineered spectrum demonstrates that localized modes can be controlled efficiently, an important step toward continuously tunable SHE driven auto-oscillators.

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Spin Dynamics in Ferromagnetic Resonance for Nano-Sized Magnetic Dot Arrays: Metrology and Insight Into Magnetization Dynamics

Cited by 16 publications

References 7 publications

Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

Microwave absorption properties of permalloy nanodots in the vortex and quasi-uniform magnetization states

A Strategy to Modulate the Bending Coupled Microwave Magnetism in Nanoscale Epitaxial Lithium Ferrite for Flexible Spintronic Devices

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

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