Controlling nanomagnet magnetization dynamics via magnetoelastic coupling

Yahagi, Y.; Harteneck, B.; Cabrini, Stefano; Schmidt, Holger

doi:10.1103/physrevb.90.140405

Cited by 65 publications

(74 citation statements)

References 29 publications

(34 reference statements)

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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: 79%

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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Section: Introductionmentioning

confidence: 79%

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

et al. 2016

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“…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.…”

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confidence: 99%

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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“…4a. 24 As expected, the nonmagnetic modes in the sum channel showed no observable field dependence even at the crossover points (not shown), justifying the simplifying assumption of the effective field approach to neglect the back-action of the magnetization on the elastic motion. The magnetic signal in the difference channel, on the other hand, shows complex multimode spectra (Fig.…”

Section: Al Arraymentioning

confidence: 50%

“…An antireflection (AR) coating of 110-nm hafnium oxide layer was commercially deposited on (100) silicon in order to enhance the magnetooptic signal. 8,24,25 The nanomagnetic array was defined on the AR coated substrate with electron beam lithography, followed by electron beam evaporation and a liftoff process. The major and minor diameters of the elliptic disks are 140 and 80 nm, respectively, as determined with a scanning electron micrograph (Fig.…”

Section: Samples and Methodsmentioning

confidence: 99%

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Control of the magnetization dynamics in patterned nanostructures with magnetoelastic coupling

et al. 2015

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We review the influence of the magnetoelastic coupling with surface acoustic waves (SAWs) on the dynamic magnetic response of a periodic nanomagnet array. In addition to exciting the magnetization precession, an ultrafast laser pulse generates multiple SAW modes whose frequencies are determined by the array pitch. As a result, strong pinning of the magnetization precession frequency at the crossover points with the SAWs is observed over an extended field range. The complex spin wave spectrum can be analyzed in frequency and momentum spaces using finite element analysis emulating generation of SAWs. The magnetic response of the nanomagnets was then correctly reproduced with micromagnetic simulations taking into account additional magnetoelastic energy terms. This finding demonstrates control of the nanomagnet dynamics with the array geometry via magnetoelastic coupling, even when the magnetostatic interaction between the magnets is negligible.

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Controlling nanomagnet magnetization dynamics via magnetoelastic coupling

Cited by 65 publications

References 29 publications

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

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

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

Control of the magnetization dynamics in patterned nanostructures with magnetoelastic coupling

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