Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque

Collet, Martin; Milly, Xavier de; Kelly, Olivier d'Allivy; Naletov, V. V.; Bernard, Rozenn; Bortolotti, Paolo; Youssef, J. Ben; Demidov, V. E.; Demokritov, S. O.; Prieto, José Luis Rodríguez-Villasante y; Muñoz, Manuel; Cros, Vincent; Anane, A.; Loubens, G. de; Klein, O.

doi:10.1038/ncomms10377

Cited by 249 publications

(264 citation statements)

References 36 publications

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“…The relatively high spin-mixing conductance combined with very low Gilbert damping (comparable with the best reported values of other metallic ferromagnets) make Pt/LSMO an attractive system for spintronic applications such as spin Hall memories 7 and oscillators. 10,[46][47][48][49] Lastly, these results indicate that LSMO is a promising perovskite building block for all-oxide multifuncitonal high-frequency spintronics devices.…”

Section: -5mentioning

confidence: 78%

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Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

et al. 2016

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We report ferromagnetic resonance measurements of magnetic anisotropy and damping in epitaxial La0.7Sr0.3MnO3 (LSMO) and Pt capped LSMO thin films on SrTiO3 (001) substrates. The measurements reveal large negative perpendicular magnetic anisotropy and a weaker uniaxial in-plane anisotropy that are unaffected by the Pt cap. The Gilbert damping of the bare LSMO films is found to be low α = 1.9(1) × 10−3, and two-magnon scattering is determined to be significant and strongly anisotropic. The Pt cap increases the damping by 50% due to spin pumping, which is also directly detected via inverse spin Hall effect in Pt. Our work demonstrates efficient spin transport across the Pt/LSMO interface.

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Section: -5mentioning

confidence: 78%

“…To date, significant focus has been set on NM/FM heterostructures comprising 3d materials 5-8 with a recent extension to yttrium iron garnet (YIG). [9][10][11] Further identification of new material platforms for the efficient generation, transmission, and conversion of spin currents is of great importance for enriching this emerging field.…”

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confidence: 99%

Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

et al. 2016

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“…However, the physical origin of this spin current tensor is different since here, it is obtained specifically for the case of a spin current induced by a thermal gradient. Very recently, self-oscillation based on spin-orbit torque was found in YIG/Pt pillars [29] and in permalloy/Pt nanowires [30]. By analogy, we may expect self-oscillation driven by a thermal spin torque as well.…”

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confidence: 88%

Thermal spin torques in magnetic insulators

Brechet

Che

et al. 2017

Phys. Rev. B

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The damping of spin waves transmitted through a two-port magnonic device implemented on a yttrium iron garnet thin film is shown to be proportional to the temperature gradient imposed on the device. The sign of the damping depends on the relative orientation of the magnetic field, the wave vector, and the temperature gradient. The observations are accounted for qualitatively and quantitatively by using an extension of the variational principle that leads to the Landau-Lifshitz equation. All parameters of the model can be obtained by independent measurements. DOI: 10.1103/PhysRevB.95.104432 The discovery of giant magnetoresistance (GMR) revolutionized information storage technology [1,2] and the spin-transfer torque (STT), predicted two decades ago by Slonczewski [3] and Berger [4], may reshape once again the magnetic memory industry [5]. The concept of a heat-driven spin torque, or thermal spin-transfer torque (TST), has been suggested [6][7][8] and opened the world of spin caloritronics. Magnetic insulators are ideal for studying the fundamentals of spin caloritronics, because they are free of the effect of heat on charge transport. Here, we demonstrate that a spin torque can be induced in magnetic insulators by applying a thermal gradient. The effect is not linked to spin-dependent transport at interfaces since we observe a heat-driven contribution to damping of magnetization waves on a millimeter scale. We show that by adding to M(r) the bound magnetic current (∇ × M) as state variable, the variational principle that yields the Landau-Lifshitz equation predicts the presence of a thermal spin torque, from which we derive an expression for spin currents in insulators. Our experiments verify the key predictions of this model. Thermodynamics can predict a link between heat and magnetization, but cannot determine the strength of the effect [9].Spin caloritronics studies the interplay of spin, charge, and heat transport [10]. As the spin dependence of the electrical conductivity proved to be important since it gives rise to GMR, the spin dependence of other transport parameters has been investigated, such as that of the Seebeck [11] and Peltier coefficients [12]. The combination of heat with spin and charge transport gained widespread attention owing to studies of the spin Seebeck effect [13,14]. The STT effect which uses a spinpolarized electrical current has shown promising applications, e.g., in magnetic memories (STT-MRAM). It was already established that heat flowing through a ferromagnetic metal can generate a diffusive spin current [15] which induces a spin torque when flowing through a magnetic nanostructure [6]. Experimentally, this effect was studied in Co/Cu/Co spin valve nanowires by observing the change in the switching * haiming.yu@buaa.edu.cn † jean-philippe.ansermet@epfl.ch field of magnetization due to a local thermal gradient [7]. It was later shown that heat couples to magnetization dynamics [16][17][18]. The effect of heat on magnetization was also found in magnetic tunnel junctions [19] and...

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“…The combination of the spin-Hall effect and the spintransfer torque may be used to compensate the magnetic damping of a ferromagnet, facilitating precession of the macroscopic magnetization by the application of a direct current [1][2][3][4][5] . Such a device, a spin-Hall oscillator, is patterned in a simple current in-plane geometry and contains no tunnel barriers.…”

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confidence: 99%

“…Such a device, a spin-Hall oscillator, is patterned in a simple current in-plane geometry and contains no tunnel barriers. The ability of the spin-Hall effect to apply a spin-current transverse to the chargecurrent enables the use of conducting magnetic materials as well as low-damping, insulating materials like yttriumiron-garnet (YIG) 5 . This is in contrast to conventional spin-torque nano-oscillators where a spin-polarized current is passed into a conducting ferromagnetic layer 6 .…”

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confidence: 99%

Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators

Langenfeld

Tshitoyan

Fang

et al. 2016

Applied Physics Letters

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We investigate magnetization dynamics in a spin-Hall oscillator using a direct current measurement as well as conventional microwave spectrum analysis. When the current applies an anti-damping spin-transfer torque, we observe a change in resistance which we ascribe to the excitation of incoherent exchange magnons. A simple model is developed based on the reduction of the effective saturation magnetization, quantitatively explaining the data. The observed phenomena highlight the importance of exchange magnons on the operation of spin-Hall oscillators.The combination of the spin-Hall effect and the spintransfer torque may be used to compensate the magnetic damping of a ferromagnet, facilitating precession of the macroscopic magnetization by the application of a direct current 1-5 . Such a device, a spin-Hall oscillator, is patterned in a simple current in-plane geometry and contains no tunnel barriers. The ability of the spin-Hall effect to apply a spin-current transverse to the chargecurrent enables the use of conducting magnetic materials as well as low-damping, insulating materials like yttriumiron-garnet (YIG) 5 . This is in contrast to conventional spin-torque nano-oscillators where a spin-polarized current is passed into a conducting ferromagnetic layer 6 . Despite being attractive due to their geometric simplicity and flexibility in choice of magnetic materials, for spin-Hall oscillators to become competitive with conventional spin-torque nano-oscillators, sources of damping such as spin-pumping 7 and multi-magnon scattering via exchange magnons 8,9 should be addressed in order to reduce the linewidth and increase the power generation efficiency. In this Letter we show that the current induced excitation of incoherent exchange magnons can be observed using a direct current measurement. We find a change in the sample resistance which correlates with the reduction of saturation magnetization taken from our spectroscopy measurements, similar to previously reported results 9 . Both phenomena are consistent within a simple model only utilizing the precession cone-angle of the auto-oscillatory exchange magnons.The sample is a Pt(3)/Py(4)/AlO x (1.6) trilayer deposited by d.c. magnetron sputtering onto a MgO substrate. Numbers in parentheses give thicknesses in nanometers. The multilayer is patterned into a 500 nm × 6 µm bar via electron-beam lithography and subsequent Ar ion milling. Adjacent evaporated Cr(5)/Au(50) pads a) current address: Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany b) ajf1006@cam.ac.uk serve as contact pads. When current is applied to this structure, the portion of the current flowing inside the heavy metal (platinum) generates an out-of-plane spincurrent via the spin-Hall effect (SHE). This spin-current exerts a spin-transfer torque (STT) on the magnetization of the ferromagnetic layer (permalloy) 10,11 , which can oppose the magnetic damping, leading to a change in the Gilbert damping parameter α 12,13 :Here, α 0 is the pristine damping parameter, j c,hm is the charge-curren...

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Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque

Cited by 249 publications

References 36 publications

Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

Magnetic anisotropy, damping, and interfacial spin transport in Pt/LSMO bilayers

Thermal spin torques in magnetic insulators

Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators

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