Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength

Savochkin, I. V.; Jäckl, M.; Belotelov, V. I.; Акимов, И. А.; Kozhaev, M. A.; Sylgacheva, D. A.; Chernov, A. I.; Shaposhnikov, A. N.; Prokopov, A. R.; Berzhansky, V. N.; Yakovlev, D. R.; Zvezdin, A. K.; Bayer, М.

doi:10.1038/s41598-017-05742-x

Cited by 62 publications

(51 citation statements)

References 31 publications

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“…In experiments described in [29,30] the optical pumping was realized in thin bismuth iron-garnet films [33] excited magnetic field h was about 10 Oe, so the bandgap was very small and due to the damping no Floquet states were observed. But the pump incidence angle was 17°, and main effect of amplitude increasing was from the right part of Eq.…”

Section: Figure 1 Excitation Of the Magnetization Precession In An Imentioning

confidence: 99%

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Optically pumped Floquet states of magnetization in ferromagnets

2019

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Floquet states have been subject of great research interest since Zel'dovich's pioneering work on the quasienergy of a quantum system subject to a temporally periodic action. Nowadays periodic modulation of the system Hamiltonian is mostly achieved by microwaves leading to novel exciting phenomena in condensed matter physics: Floquet topological insulators, chiral edge states etc. On the other hand, nonthermal optical control of magnetization at picosecond time scales is currently a highly appealing research topic for potential applications in magnetic data storage. Here we combine these two concepts to investigate Floquet states in the system of exchange-coupled spins in a ferromagnet. We periodically perturb the magnetization of an iron-garnet film by a train of circularly-polarized femtosecond laser pulses hitting the sample at 1 GHz repetition rate and monitor the magnetization dynamics behaving like a Floquet state. An external magnetic field allows tuning of the Floquet states leading to a pronounced increase of the precession amplitude by one order of magnitude at the center of the Brillouin zone, i.e. when the precession frequency is a multiple of the laser pulse repetition rate. Floquet states might potentially allow for parametric generation of magnetic oscillations. The observed phenomena expand the capabilities of coherent ultrafast optical control of magnetization and pave a way for their application in quantum computation or data processing.

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Section: Figure 1 Excitation Of the Magnetization Precession In An Imentioning

confidence: 99%

“…Recently, influence of the periodic pumping has been demonstrated [29,30]. It was shown that a train of optical pump pulses can drive the magnetization within the illuminated area thereby exciting spin waves and their amplitude can be significantly increased if the magnetization oscillation frequency synchronized with the laser pulses.…”

Section: Introductionmentioning

confidence: 99%

Optically pumped Floquet states of magnetization in ferromagnets

2019

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“…The inverse Faraday effect (IFE) provides a new way for efficient control of spins at GHz and THz rates 1 . Circularly polarized laser pulses can induce the IFE effective magnetic field of about 10 2 -10 4 Oe in a magnetic dielectric and excite the magnetization precession leading to magnetostatic spin waves [9][10][11][12][13][14][15][16][17][18] . By now, the IFE has been investigated only in a freestanding crystals and films on a substrate.…”

Section: Introductionmentioning

confidence: 99%

Giant peak of the Inverse Faraday effect in the band gap of magnetophotonic microcavity

Kozhaev¹,

Chernov²,

Sylgacheva³

et al. 2018

Sci Rep

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Optical impact on the spin system in a magnetically ordered medium provides a unique possibility for local manipulation of magnetization at subpicosecond time scales. One of the mechanisms of the optical manipulation is related to the inverse Faraday effect (IFE). Usually the IFE is observed in crystals and magnetic films on a substrate. Here we demonstrate the IFE induced by fs-laser pulses in the magnetic film inside the magnetophotonic microcavity. Spectral dependence of the IFE on the laser pulse wavelength in the band gap of the magnetophotonic microcavity has a sharp peak leading to a significant enhancement of the IFE. This phenomenon is explained by strong confinement of the electromagnetic energy within the magnetic film. Calculated near field distribution of the IFE effective magnetic field indicates its subwavelength localization within 30 nm along the film thickness. These excited volumes can be shifted along the sample depth via e.g. changing frequency of the laser pulses. The obtained results open a way for ultrafast optical control of magnetization at subwavelength scales.

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“…First of all, it allows to influence on the magnetization locally, within the focused laser spot, that can be easily shifted along the sample [11,12]. The micron size area of the sample where spins interact with photons can operate like a point source of magnons [13][14][15] . Variation of the laser spot shape and size provides tunability in terms of the type and spectrum of the generated spin waves.…”

Section: Introductionmentioning

confidence: 99%

“…For example, one could switch between surface and backward volume spin waves by simply reducing diameter of the laser spot [16,17]. Moreover, passing from excitation with a single pulse to the multiple pulse excitation gives additional degree of freedom leading to enhancement of the spin waves amplitude, tunability of their spectrum and directivity of the magnon source [14,15].…”

Section: Introductionmentioning

confidence: 99%

Control of the phase of the magnetization precession excited by circularly polarized femtosecond-laser pulses

Chernov¹,

Kozhaev²,

Khramova³

et al. 2018

Photon. Res.

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The inverse Faraday effect induced in magnetic films by ultrashort laser pulses allows excitation and control of spins at GHz and sub-THz frequencies. Frequency of the excited magnetization precession is easily tunable by the external magnetic field. On the other hand, phase of the precession hardly depends on magnetic field. Here we demonstrate an approach for the control of the precession phase by variation of the incidence angle of the laser pulses. In particular, theoretical consideration states that the phase increases with increase of the incidence angle and for small angles this relation is a direct proportionality. Experimental studies confirm this conclusion and provide shift of phase by about 4 deg. for the declination of the incidence angle by 15 deg. from the normal. This study provides a simple way for additional manipulation with optically excited magnetization dynamics, which is of importance for different spintronic applications.

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Generation of spin waves by a train of fs-laser pulses: a novel approach for tuning magnon wavelength

Cited by 62 publications

References 31 publications

Optically pumped Floquet states of magnetization in ferromagnets

Optically pumped Floquet states of magnetization in ferromagnets

Giant peak of the Inverse Faraday effect in the band gap of magnetophotonic microcavity

Control of the phase of the magnetization precession excited by circularly polarized femtosecond-laser pulses

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