Anomalously Damped Heat-Assisted Route for Precessional Magnetization Reversal in an Iron Garnet

Davies, C. S.; Prabhakara, Kiran Horabail; Davydova, Margarita; Zvezdin, K. A.; Shapaeva, T. B.; Wang, S.; Zvezdin, A. K.; Kirilyuk, Andrei; Rasing, T.H.M.; Kimel, A. V.

doi:10.1103/physrevlett.122.027202

Cited by 47 publications

(37 citation statements)

References 51 publications

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“…A large magnetooptical contrast is achieved by bismuth substitution [28], which connects this workhorse of magnon spintronics [29,30] and spin caloritronics [31] to optomagnetism. Recent publications on ferrimagnetic garnets reported magnetization dynamics via thermally induced crystalline anisotropy modification [23,32,33], similar to previous work in antiferromagnets [34][35][36]. More specifically, optically excited coherent and incoherent phonons are reported to generate spin waves (SWs) [27,37,38].…”

supporting

confidence: 76%

“…Here, we present nondestructive UXRD measurements on the very same Bi:YIG film [38], to quantify the lattice dynamics upon below-band-gap femtosecond laser excitation with fluences up to 100 mJ/cm 2 . This corresponds to intensities, which are typical of experiments that manipulate magnetization in insulators by femtosecond light pulses [19,33,37,38], and we find a pronounced quadratic fluence dependence of the strain amplitude that quantifies coherent and incoherent phonons as propagating strain pulses and localized thermal expansion, respectively. The strain amplitude is inversely proportional to the pump pulse duration, which indicates a short lifetime of the intermediate state during the two-photon excitation.…”

supporting

confidence: 53%

“…From this, we determine the two-photon absorption coefficient β ≈ 2 cm/GW for exciting Bi 1 Y 2 Fe 5 O 12 at 800 nm. We believe that our quantitative evaluation of the strain generated by two-photon absorption is particularly important for a full understanding of lightdriven spin manipulation in magnetic insulators [23,27,[32][33][34][35][36][37][38], but it has more general relevance for ultrafast science on supposedly nonabsorbing or transparent matter. The large peak intensities around 1 TW/cm 2 necessary to drive 0.1% strain can be achieved both by high pump fluences and short pulse durations.…”

Section: -3mentioning

confidence: 99%

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Measurement of transient strain induced by two-photon excitation

Zeuschner

Pudell

Reppert

et al. 2020

Phys. Rev. Research

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By ultrafast x-ray diffraction we quantify the strain from coherent and incoherent phonons generated by one-and two-photon absorption. We investigated the ferrimagnetic insulator bismuth-doped yttrium iron garnet, which is a workhorse for laser-induced spin dynamics that may be excited indirectly via phonons. We identify the two-photon absorption by the quadratic intensity dependence of the transient strain and confirm a short lifetime of the intermediate state via the inverse proportional dependence on the pump-pulse duration. We determine the two-photon absorption coefficient using the linear relation between strain and absorbed energy density. For large intensities of about 1 TW/cm 2 considerable strain amplitudes of 0.1% are driven exclusively by two-photon absorption.

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supporting

confidence: 76%

supporting

confidence: 53%

Section: -3mentioning

confidence: 99%

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Measurement of transient strain induced by two-photon excitation

Zeuschner

Pudell

Reppert

et al. 2020

Phys. Rev. Research

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“…This behavior in metallic magnets is qualitatively in agreement with theoretical studies that predict an increase in damping, when the static temperature of the sample increases towards T C [63,64]. However, in dielectric iron garnet, the increase of the sample temperature induced by a 800 nm pump pulse with E pump = 20 mJ cm −2 cannot exceed 10 K [52,56,65] and the sample temperature remains very far from T C . This is reflected by no, or only very low, dependence of the damping on E pump , which is an additional advantage of laser-induced SWs in magnetic insulators.…”

Section: Results and Disccussionsupporting

confidence: 89%

“…is not at the origin of the excitation. The excitation of the SSWs is related to an ultrafast change of magnetic anisotropy induced by incoherent and coherent phonons due to the temperature dependence of the magnetic anisotropy constants [51,52] and inverse magnetostriction [53][54][55][56], respectively. The coherent and incoherent phonons are generated via the absorption of the pump photons by the phonon-assisted electronic d-d transitions simultaneously by one-and two-photon absorption processes [56].…”

Section: Results and Disccussionmentioning

confidence: 99%

Damping of Standing Spin Waves in Bismuth-Substituted Yttrium Iron Garnet as Seen via the Time-Resolved Magneto-Optical Kerr Effect

et al. 2019

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We investigate spin-wave resonance modes and their damping in insulating thin films of bismuthsubstituted yttrium iron garnet by performing femtosecond magneto-optical pump-probe experiments. For large magnetic fields in the range below the magnetization saturation, we find that the damping of high-order standing spin-wave (SSW) modes is about 40 times lower than that for the fundamental one. The observed phenomenon can be explained by considering different features of magnetic anisotropy and exchange fields that, respectively, define the precession frequency for fundamental and high-order SSWs. These results provide further insight into SSWs in iron garnets and may be exploited in many new photomagnonic devices.

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Laser‐Induced Transient Anisotropy and Large Amplitude Magnetization Dynamics in a Gd/FeCo Multilayer

Blank

Hermanussen

Lichtenberg

et al. 2022

Adv Materials Inter

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Ultrafast laser‐induced dynamics in a ferrimagnetic gadolinium iron cobalt (Gd/FeCo) multilayer with a magnetization compensation temperature of TM = 320 K is studied at room temperature as a function of laser‐fluence and strength of the applied magnetic field. The dynamics is found to be substantially different from that in archetypical GdFeCo alloys, and depending on the laser fluence one can distinguish two different regimes. At low laser fluence (⩽1.6 mJ cm‐2), ultrafast laser excitation of the medium triggers spin precession of an extraordinary large amplitude reaching over 30°. At high laser fluence (⩾2.2 mJ cm‐2), the pump heats the medium over the magnetization compensation point, spin precession reduces significantly in amplitude and the process of field‐assisted reversal of magnetization of Gd and FeCo is launched. It is argued that such a distinctly different laser‐induced magnetization dynamics in the multilayers compared to the alloys is due to the symmetry breaking at the numerous interfaces, giving rise to additional surface anisotropy. The temperature dependence of the latter is found to be the key ingredient in the mechanism of ultrafast laser‐induced magnetization dynamics in ferrimagnetic multilayers. Controlling the amount and properties of interfaces in multilayers can thus serve as a mean to achieve efficient ultrafast all‐optical control of magnetism.

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Anomalously Damped Heat-Assisted Route for Precessional Magnetization Reversal in an Iron Garnet

Cited by 47 publications

References 51 publications

Measurement of transient strain induced by two-photon excitation

Measurement of transient strain induced by two-photon excitation

Damping of Standing Spin Waves in Bismuth-Substituted Yttrium Iron Garnet as Seen via the Time-Resolved Magneto-Optical Kerr Effect

Laser‐Induced Transient Anisotropy and Large Amplitude Magnetization Dynamics in a Gd/FeCo Multilayer

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