Coherent shear phonon generation and detection with picosecond laser acoustics

Matsuda, Osamu; Wright, Oliver B.; Hurley, David H.; Gusev, Vitalyi; Shimizu, K.

doi:10.1103/physrevb.77.224110

Cited by 63 publications

(63 citation statements)

References 48 publications

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“…In the experiments, we do not see any resonant effects at the B values that correspond to the resonance of f M being equal to the frequency of localized TA phonons. This is not surprising because the optical pump excitation does not excite shear strain and correspondingly TA phonons in the present high symmetry geometry [27,28]. However, we could expect the generation of LA and TA phonons from the magnetization precession, as has been observed in conventional microwave-driven magnetoacoustic experiments [29].…”

Section: Resonant Driving Of Magnetization Precession Physical mentioning

confidence: 71%

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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Section: Resonant Driving Of Magnetization Precession Physical mentioning

confidence: 71%

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

et al. 2015

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“…In the beginning, we restrict our simulations to the photoelastic effect in the 100-nm GaN bulklike layer and the interface mechanism, since the complex index of refraction dispersion is known only for bulk material [20] but not for the QW. A model to calculate the reflectivity change ΔR normalized to the unperturbed value R 0 , which covers both effects, was developed before and is applied here to our experiment [12,21]. We use an input acoustic pulse like that shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Picosecond Acoustics in Single Quantum Wells of Cubic GaN/(Al,Ga)N

et al. 2017

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A picosecond acoustic pulse is used to study the photoelastic interaction in single zinc-blende GaN=Al x Ga 1−x N quantum wells. We use an optical time-resolved pump-probe setup and demonstrate that tuning the photon energy to the quantum well's lowest electron-hole transition makes the experiment sensitive to the quantum well only. Because of the small width, its temporal and spatial resolution allows us to track the few-picosecond-long transit of the acoustic pulse. We further deploy a model to analyze the unknown photoelastic coupling strength of the quantum well for different photon energies and find good agreement with the experiments.

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“…for the region of z < 0 and z 0 > 0 [21,30,39]. Δεz; t is, for the time being, assumed to be composed of a sum of the photoelastic contribution ε pe and the surface displacement contribution ε d .…”

Section: Theorymentioning

confidence: 99%

Ultrafast ellipsometric interferometry for direct detection of coherent phonon strain pulse profiles

et al. 2013

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We describe an ultrafast optical technique to quantitatively detect picosecond ultrasonic displacements of solid surfaces, thus giving access to the longitudinal strain pulse shape. Transient optical reflectance changes recorded at oblique optical incidence with a common-path interferometric configuration based on ultrafast ellipsometry monitor gigahertz coherent phonon pulses. We demonstrate for a tungsten film the quantitative extraction of the strain pulse shape free of distortions arising from the photoelastic effect, and analyze the results with the two-temperature model to obtain the value g ≈ 3 × 10 17 Wm −3 K −1 for the electron-phonon coupling constant. Analysis of the data also reveals a thermo-optic contribution.

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Coherent shear phonon generation and detection with picosecond laser acoustics

Cited by 63 publications

References 48 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

Picosecond Acoustics in Single Quantum Wells of Cubic GaN/(Al,Ga)N

Ultrafast ellipsometric interferometry for direct detection of coherent phonon strain pulse profiles

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