Picosecond inverse magnetostriction in galfenol thin films

Jäger, J. V.; Scherbakov, A. V.; Linnik, T. L.; Yakovlev, D. R.; Wang, M.; Wadley, P.; Holý, V.; Cavill, S. A.; Akimov, A. V.; Rushforth, A. W.; Bayer, М.

doi:10.1063/1.4816014

Cited by 65 publications

(69 citation statements)

References 34 publications

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“…The squares show the measured dependence of the precession frequency in the studied Galfenol film on B, interpolated linearly by the solid line, which is in good agreement with previous experiments [19,24]. The horizontal dashed lines indicate the frequencies f Ri of the phonon modes in the SL1 and SL2 cavities.…”

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confidence: 74%

“…The major fraction of generated phonons leaves the Galfenol film with a sound velocity on a time scale of ∼10 ps, but phonons with frequencies f = f Ri remain localized in the FP cavities for a longer time. The calculations for the cavity formed by SL1 at f R1 give a remarkably high value for the decay time of τ R1 ∼ 10 ns, which is three orders of magnitude longer than the escape time for nonresonant phonons from the cavity and two orders of magnitude longer than the lifetime of the free magnetization precession in this experimental geometry [19,24]. The localized phonons drive the magnetization precession at f = f Ri , and this driving force will last during the leakage time τ R1 .…”

Section: Resonant Driving Of Magnetization Precession Physical mentioning

confidence: 99%

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Resonant driving of magnetization precession in a ferromagnetic layer by coherent monochromatic phonons

et al. 2015

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We realize resonant driving of the magnetization precession by monochromatic phonons in a thin ferromagnetic layer embedded into a phononic Fabry-Pérot resonator. A femtosecond laser pulse excites resonant phonon modes of the structure in the 10−40 GHz frequency range. By applying an external magnetic field, we tune the precession frequency relative to the frequency of the phonons localized in the cavity and observe an enormous increase in the amplitude of the magnetization precession when the frequencies of free magnetization precession and phonons localized in the cavity are equal. The continual miniaturization of magnetic devices down to the nanometer scale has opened new horizons in data storage [1], computing [2,3], sensing [4,5], and medical technologies [6]. Progress in nanomagnetism is stimulated by emerging technologies, where methods to control magnetic excitations on the nanometer spatial and picosecond temporal scales include optical [7,8], electrical [8], and micromechanical [9] techniques. To realize ultrafast nanomagnetism on the technological level, new physical principles to efficiently induce and control magnetic excitations are required, and this remains a challenging task. A new basic approach to this problem would be to explore nanoscale magnetic resonance phenomena-resonant driving and monitoring of magnetic excitations-which is widely used nowadays in traditional magnetism for microscopy, medicine, and spectroscopy. The typical frequencies f M of the magnetic resonances [e.g., the ferromagnetic resonance (FMR) in ferromagnetic and ferrimagnetic materials] are in the GHz and sub-THz frequency ranges. The traditional methods to scan magnetic excitations at these frequencies use microwaves, but due to the requirement of massive microwave resonators providing long wavelength radiation, they cannot provide high-speed control of magnetization locally on the nanoscale.Among various emerging techniques in nanomagnetism, the application of stress to magnetostrictive ferromagnetic layers has been shown to be an effective, low-power method for controlling magnetization: Applying in-plane stress in stationary experiments enables irreversible switching of the magnetization vector [10]; the injection of picosecond strain pulses induces free precession of the magnetization [11]; excitation of quantized elastic waves in a membrane enables driving of the magnetization at GHz phonon frequencies [12]; and surface acoustic waves can be used to control the magnetic dynamics in ferromagnetic nanostructures [13][14][15]. In the present Rapid Communication, we examine the interaction of a high-frequency (10−40 GHz) magnetic resonance in a magnetostrictive ferromagnetic film with an elastic harmonic excitation in the form of a localized phonon mode, and demonstrate how this interaction becomes significantly stronger at resonance conditions. Our device consists of a ferromagnetic layer embedded into a phonon Fabry-Pérot (FP) cavity. Such a cavity possesses quantized resonances for elastic waves (i.e., phonons) at f...

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confidence: 74%

Section: Resonant Driving Of Magnetization Precession Physical mentioning

confidence: 99%

Resonant driving of magnetization precession in a ferromagnetic layer by coherent monochromatic phonons

et al. 2015

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“…[13] as a possible impact for triggering the magnetization precession. Later, coherent phonons have been shown to be an efficient stimulus for changing the MCA in experiments with picosecond strain pulses, when the magnetization precession is excited without direct optical excitation of the ferromagnet [14,15], and with optically excited surface acoustic waves [16,17]. In these experiments, the amplitude of the precession was large enough that we can assume that the coherent phonons may also have a significant contribution when the metal ferromagnet is excited directly by an optical pulse.…”

Section: Introductionmentioning

confidence: 80%

“…strain-assisted control of magnetization by electric field [22]. In the experiments with picosecond stain pulses injected into a Galfenol film from a GaAs substrate, the strain effectively triggers high-amplitude magnetization precession [15]. However, direct optical excitation of magnetization dynamics of Galfenol has not been studied so far and the comparative role of coherent and non-coherent phonons in the changes of the MCA remains unexplored.…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast changes of magnetic anisotropy driven by laser-generated coherent and noncoherent phonons in metallic films

et al. 2016

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. (2016) Ultrafast changes of magnetic anisotropy driven by laser-generated coherent and noncoherent phonons in metallic films. Physical Review B, 93 (21 A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. ABSTRACTUltrafast optical excitation of a metal ferromagnetic film results in a modification of the magnetocrystalline anisotropy and induces the magnetization precession. We consider two main contributions to these processes: an effect of non-coherent phonons, which modifies the temperature dependent parameters of the magneto-crystalline anisotropy; and coherent phonons in the form of a strain contributing via inverse magnetostriction. Contrary to the earlier experiments with high symmetry ferromagnetic structures, where these mechanisms could not be separated, we study the magnetization response to femtosecond optical pulses in the low-symmetry magnetostrictive Galfenol film so that it is possible to separate the coherent and non-coherent phonon contributions. By choosing certain experimental geometry and external magnetic field, we can distinguish the contribution from a specific mechanism. Theoretical analysis and numerical calculations are used to support the experimental observations and proposed model.

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Microstructure evolution, magnetostrictive and mechanical properties of (Fe83Ga17)99.9(NbC)0.1 alloy ultra-thin sheets

et al. 2019

J Mater Sci

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Picosecond inverse magnetostriction in galfenol thin films

Cited by 65 publications

References 34 publications

Resonant driving of magnetization precession in a ferromagnetic layer by coherent monochromatic phonons

Resonant driving of magnetization precession in a ferromagnetic layer by coherent monochromatic phonons

Ultrafast changes of magnetic anisotropy driven by laser-generated coherent and noncoherent phonons in metallic films

Microstructure evolution, magnetostrictive and mechanical properties of (Fe83Ga17)99.9(NbC)0.1 alloy ultra-thin sheets

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