Generation of exchange magnons in thin ferromagnetic films by ultrashort acoustic pulses

Besse, Valentin; Golov, A.V.; Vlasov, V. S.; Alekhin, Alexandr; Kuzmin, Dmitry A.; Bychkov, Igor V.; Котов, Л. Н.; Temnov, Vasily V.

doi:10.1016/j.jmmm.2019.166320

Cited by 29 publications

(19 citation statements)

References 42 publications

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“…Relaxation occurs when the pumped energy by phonon is no longer sufficient to compensate for the dissipated energy. The overall agreement of experiment and theory suggests that our assumption of a uniform spin mode is correct, although the existence of the lowest exchange magnon cannot be completely excluded ( 29 ).…”

Section: Discussionmentioning

confidence: 70%

High-frequency magnetoacoustic resonance through strain-spin coupling in perpendicular magnetic multilayers

Zhang

Zhu

et al. 2020

Sci. Adv.

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It is desirable to experimentally demonstrate an extremely high resonant frequency, assisted by strain-spin coupling, in technologically important perpendicular magnetic materials for device applications. Here, we directly observe the coupling of magnons and phonons in both time and frequency domains upon femtosecond laser excitation. This strain-spin coupling leads to a magnetoacoustic resonance in perpendicular magnetic [Co/Pd]n multilayers, reaching frequencies in the extremely high frequency (EHF) band, e.g., 60 GHz. We propose a theoretical model to explain the physical mechanism underlying the strain-spin interaction. Our model explains the amplitude increase of the magnetoacoustic resonance state with time and quantitatively predicts the composition of the combined strain-spin state near the resonance. We also detail its precise dependence on the magnetostriction. The results of this work offer a potential pathway to manipulating both the magnitude and timing of EHF and strongly coupled magnon-phonon excitations.

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Section: Discussionmentioning

confidence: 70%

High-frequency magnetoacoustic resonance through strain-spin coupling in perpendicular magnetic multilayers

Zhang

Zhu

et al. 2020

Sci. Adv.

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“…A question arises under which conditions the crossing between dispersion curves for longitudinal phonons and inertial magnons can occur. Whereas for realistic magnetic fields the acoustic dispersion always intersects the lower FMRbranch at a frequency close to FMR frequency [42], the crossing of the upper nutation brunch is less obvious. It is possible to quantify the criterion for magnetoelastic crossing with nutation magnons analytically.…”

Section: Excitation Mechanisms Of Inertial Exchange Magnonsmentioning

confidence: 91%

“…In order to excite k = 0 exchange magnon modes one would need to have either spatially localized and instantaneous stimuli [10] or any other source of effective magnetic field characterized by spectral and spatial overlap with investigated magnon modes. The letter can be provided through ultrashort large-amplitude acoustic pulses [40,41] producing effective magneto-elastic fields rapidly varying in time and space [42]. Acoustic pulses propagating through a thin ferromagnetic sample at an acoustic velocity v are quantified by a linearized dispersion relation ω ac = vk.…”

Section: Excitation Mechanisms Of Inertial Exchange Magnonsmentioning

confidence: 99%

Anatomy of inertial magnons in ferromagnets

Lomonosov,

Temnov,

Wegrowe

2021

Preprint

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We analyze dispersion relations of magnons in ferromagnetic nanostructures with uniaxial anisotropy taking into account inertial terms, i.e. magnetic nutation. Inertial effects are parametrized by damping-independent parameter β, which allows for an unambiguous discrimination of inertial effects from Gilbert damping parameter α. The analysis of magnon dispersion relation shows its two branches are modified by the inertial effect, albeit in different ways. The upper nutation branch starts at ω = 1/β, the lower branch coincides with FMR in the long-wavelength limit and deviates from the zero-inertia parabolic dependence ≃ ωF M R + Dk 2 of the exchange magnon. Taking a realistic experimental geometry of magnetic thin films, nanowires and nanodiscs, magnon eigenfrequencies, eigenvectors and Q-factors are found to depend on the shape anisotropy. The possibility of phase-matched magneto-elastic excitation of nutation magnons is discussed and the condition was found to depend on β, exchange stiffness D and the acoustic velocity.

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“…These include colloidal nanocrystals, [138] plasmonic, [139,140] or magnonic structures. [141][142][143]…”

Section: Picosecond Acousticsmentioning

confidence: 99%

Remote Phonon Control of Quantum Dots and Other Artificial Atoms

2021

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To exploit the full potential of chips for quantum technologies, it is worth considering all possible opportunities offered by the solid state. The aspect covered in this article is the use of phononic fields to remotely influence the optical properties of artificial atoms. The three most commonly used strain sources are discussed, that is, mechanical resonators, surface acoustic waves, and picosecond acoustic pulses. All three platforms are routinely interfaced with quantum dots and other qubits in basic research, which renders a first step toward large scale implementation in quantum applications. A central question regarding the interaction between lattice oscillations and the optically active artificial atoms deals with the characteristic time scales of the two components. The influence of this aspect on the expected optical response on the phononic driving is discussed. Besides well known semiconducting quantum dots and color centers that typically operate in the visible spectral range, the more recently discovered artificial atoms in layered van der Waals materials are discussed. Due to their flexibility and robustness, these crystals promise vast opportunities for future applications. Another important building block lies in superconducting qubits that allow to resonantly generate quantum phonon states and therefore establish the field of quantum acoustics.

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Generation of exchange magnons in thin ferromagnetic films by ultrashort acoustic pulses

Cited by 29 publications

References 42 publications

High-frequency magnetoacoustic resonance through strain-spin coupling in perpendicular magnetic multilayers

High-frequency magnetoacoustic resonance through strain-spin coupling in perpendicular magnetic multilayers

Anatomy of inertial magnons in ferromagnets

Remote Phonon Control of Quantum Dots and Other Artificial Atoms

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