Generation and manipulation of current-induced spin-orbit torques

Ando, Kotoji

doi:10.2183/pjab.97.025

Cited by 8 publications

(2 citation statements)

References 134 publications

(144 reference statements)

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“…A full understanding of the charge-spin conversion in such a multilayer system may require the first-principles calculations, which are beyond the scope of the current study. The FL spin Hall efficiency also increases from 0.5% to 5.9% with the interface engineering, which may be due to the change in spin-dependent disorder scattering in the samples [45]. The effective DL spin Hall conductivity of each stack is further deduced to be −3.9 × 10 5 , −4.8 × 10 5 , and −4.7 × 10 5 e 2  Ω −1 m −1 for n = 0, 1, and 2, as listed in table 1.…”

Section: St-fmr Measurementmentioning

confidence: 98%

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Song

Scheike

et al. 2023

Nanotechnology

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The demonstration of the spin-charge conversion, especially with enhanced spin Hall conductivity, is crucial for the development of energy-efficient spintronic devices such as spin-orbital torque (SOT) based magnetoresistive random access memories. In this work, fully epitaxial Ru/Cu heterostructures were fabricated with interface engineering and nanolayer insertions consisting of Cu (1nm)/Ru (1nm) structures with different numbers of periods. The atomically controlled interface was confirmed by the high-resolution high-angle annular dark-field scanning transmission electron microscopy, and the epitaxial relationship persists even in the hybrid nanolayer insertion structures. The spin current generation was detected by the measurement of unidirectional spin Hall magnetoresistance, and the effective damping-like spin Hall efficiency (ξ_DL) was further quantitatively evaluated by the spin-torque ferromagnetic resonance with thickness dependence of the ferromagnetic layer. It is found that the sharp interface Ru/Cu film has a sizeable ξ_DL of −2.2% and the insertion of Cu/Ru nanolayers at the interface can increase the ξ_DL value to −3.7%. The former could be attributed to the interface spin-orbit filtering effect and the latter may be further understood by the intrinsic contribution from the local electronic structure tuning due to the lattice distortion near the interface. A large effective spin Hall conductivity is achieved to be (3~5)×10^5 ℏ/2eΩ^(−1)m^(−1) in the epitaxial Ru/Cu hybrid nanolayers, which is in the same range as that of platinum. This work indicates that the interfacial control with hybrid nanolayer structures can extend the SOT-based materials to highly conductive metals, even with weak spin-orbit interactions, toward high stability, low cost, and low energy consumption for spintronic applications.

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Section: St-fmr Measurementmentioning

confidence: 98%

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Song

Scheike

et al. 2023

Nanotechnology

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“…The ξ FL is observed to have a substantial value and an inverse sign in relation to the ξ DL , which could be due to the changes in spin-orbital coupling by inversion symmetry breaking at the Ru 50 Mo 50 /CoFeB interface 31 and the complex spin-dependent scattering that occurs at the material interface. 32,33 The angular momentum transfer induced ferromagnetic resonance dynamics within Ru/Ni, Ru 50 Mo 50 /Ni and Ru 50 Mo 50 /Ru/Ni heterostructures have been further explored. Figures 5(a)-5(c) illustrate the examined stack structures.…”

Section: B Spin-torque Ferromagnetic Resonance Measurementsmentioning

confidence: 99%

Enhanced orbital torque efficiency in nonequilibrium Ru50Mo50(0001) alloy epitaxial thin films

Tang,

He,

Wen

et al. 2024

APL Materials

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Epitaxial thin films of fully nonequilibrium hcp-Ru50Mo50(0001) nanoalloys were prepared as a chemically disordered alloy, in which the intrinsic spin Hall effect is expected to be negligible. Structural analyses confirmed the epitaxial growth and atomic scale alloying of the films. In contrast to a tiny torque efficiency (ξDL) of ∼0.4% for Ru50Mo50/CoFeB, the ξDL for the Ru50Mo50/Ni heterostructure reached ∼30% with a long-range relaxation length. The apparent dependence of ξDL on the ferromagnetic layer can be attributed to the orbital Hall effect (OHE). Interestingly, a smaller ξDL was observed for Ru/Ni, suggesting that the nonequilibrium Ru50Mo50 enhances its OHE. Furthermore, the enhanced ξDL is maintained by inserting a Ru layer between the Ru50Mo50 and Ni layers, showing orbital transport through Ru. This finding illustrates potential applications of nonequilibrium nanoalloy films in spin orbitronics and contributes to getting insights into the understanding of the interrelationships between nanostructures and orbital transport properties.

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Spin Hall nano-oscillators based on synthetic skyrmions imprinted in Co nanodisc

et al. 2022

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Spin Hall nano-oscillators utilizing the synthetic spin textures imprinted in nanomagnets are demonstrated by numerical investigations. The imprinting is achieved by locally manipulating the magnetic anisotropy and the interfacial Dzyaloshinskii–Moriya interaction (DMI). The resulting spin texture is equivalent to a Néel-type skyrmion and is topologically stable to thermal fluctuations at finite temperatures. The eigenoscillation of the synthetic skyrmion can be activated by the spin-orbit torques induced by the spin Hall effect, and an eigenfrequency of up to ∼1.5 GHz is achieved. The eigenmode of the skyrmion resonance is found to be associated with the counter-clockwise rotational motion of the local magnetization. Our result demonstrates the working principle of using synthetic nanomagnets in spintronics applications.

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Generation and manipulation of current-induced spin-orbit torques

Cited by 8 publications

References 134 publications

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Enhanced orbital torque efficiency in nonequilibrium Ru50Mo50(0001) alloy epitaxial thin films

Spin Hall nano-oscillators based on synthetic skyrmions imprinted in Co nanodisc

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