| 1. |
- Awad, Ahmad, et al.
(författare)
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Long-range mutual synchronization of spin Hall nano-oscillators
- 2017
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2473 .- 1745-2481. ; 13, s. 292-299
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Tidskriftsartikel (refereegranskat)abstract
- The spin Hall effect in a non-magnetic metal with spin–orbit coupling injects transverse spin currents into adjacent magnetic layers, where the resulting spin transfer torque can drive spin wave auto-oscillations. Such spin Hall nano-oscillators (SHNOs) hold great promise as extremely compact and broadband microwave signal generators and magnonic spin wave injectors. Here we show that SHNOs can also be mutually synchronized with unprecedented efficiency. We demonstrate mutual synchronization of up to nine individual SHNOs, each separated by 300nm. Through further tailoring of the connection regions we can extend the synchronization range to 4μm. The mutual synchronization is observed electrically as an increase in the power and coherence of the microwave signal, and confirmed optically using micro-Brillouin light scattering microscopy as two spin wave regions sharing the same spectral content, in agreement with our micromagnetic simulations.
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| 2. |
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| 3. |
- Dürrenfeld, P., et al.
(författare)
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A 20 nm spin Hall nano-oscillator
- 2017
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Ingår i: Nanoscale. - : RSC Publishing. - 2040-3364 .- 2040-3372. ; 9:3, s. 1285-1291
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Tidskriftsartikel (refereegranskat)abstract
- Spin Hall nano-oscillators (SHNOs) are an emerging class of pure spin current driven microwave signal generators. Through the fabrication of 20 nm nano-constrictions in Pt/NiFe bilayers, we demonstrate that SHNOs can be scaled down to truly nanoscopic dimensions, with the added benefit of ultra-low operating currents and improved power conversion efficiency. The lateral confinement leads to a strong shape anisotropy field as well as an additional demagnetizing field whose reduction with increasing auto-oscillation amplitude can yield a positive current tunability contrary to the negative tunability commonly observed for localized excitations in extended magnetic layers. Micromagnetic simulations corroborate the experimental findings and suggest that the active magnetodynamic area resides up to 100 nm outside of the nano-constriction.
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| 4. |
- Yin, Yuli, et al.
(författare)
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Ferromagnetic and Spin-Wave Resonance on Heavy-Metal-Doped Permalloy Films : Temperature Effects
- 2017
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Ingår i: IEEE Magnetics Letters. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1949-307X .- 1949-3088. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Broadband ferromagnetic resonance (FMR)spectroscopy is used to study the temperature (T)and dopantconcentration dependence of the magnetodynamic properties of Permalloy (Py = Ni80Fe20)and Py-100- M-x(x) films, where the dopant M = Pt, Au, and Ag. The saturation magnetization (MS)and Gilbert damping constant (a)are determined from the uniform FMR mode, while the spin wave stiffness (D)is extracted using the first perpendicular standing spinwave mode. The temperature dependence of D is best described by a T (2) law, which suggests a noticeable effect of the itinerant character of the electrons. The spin wave stiffness is also estimated using Bloch's law and the two methods are compared. The results strongly imply that not only spin wave and Stoner excitations, but also other mechanisms contribute to the reduction of MS. The damping increases with T for all samples, but the enhancement is most pronounced for Py doped with 30 at.% Au.
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| 5. |
- Yin, Y. L., et al.
(författare)
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Ferromagnetic and Spin-Wave Resonance on Heavy-Metal-Doped Permalloy Films: Temperature Effects
- 2017
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Ingår i: Ieee Magnetics Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1949-307X .- 1949-3088. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Broadband ferromagnetic resonance (FMR)spectroscopy is used to study the temperature (T)and dopantconcentration dependence of the magnetodynamic properties of Permalloy (Py = Ni80Fe20)and Py-100- M-x(x) films, where the dopant M = Pt, Au, and Ag. The saturation magnetization (MS)and Gilbert damping constant (a)are determined from the uniform FMR mode, while the spin wave stiffness (D)is extracted using the first perpendicular standing spinwave mode. The temperature dependence of D is best described by a T (2) law, which suggests a noticeable effect of the itinerant character of the electrons. The spin wave stiffness is also estimated using Bloch's law and the two methods are compared. The results strongly imply that not only spin wave and Stoner excitations, but also other mechanisms contribute to the reduction of MS. The damping increases with T for all samples, but the enhancement is most pronounced for Py doped with 30 at.% Au.
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