| 1. |
- Kravets, Anatolii, et al.
(author)
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Effect of nanostructure layout on spin pumping phenomena in antiferromagnet/nonmagnetic metal/ferromagnet multilayered stacks
- 2017
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In: AIP Advances. - : American Institute of Physics Inc.. - 2158-3226. ; 7:5
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Journal article (peer-reviewed)abstract
- In this work we focus on magnetic relaxation in Mn80Ir20(12 nm)/Cu(6 nm)/Py(dF) antiferromagnet/Cu/ferromagnet (AFM/Cu/FM) multilayers with different thickness of the ferromagnetic permalloy layer. An effective FM-AFM interaction mediated via the conduction electrons in the nonmagnetic Cu spacer - the spin-pumping effect - is detected as an increase in the linewidth of the ferromagnetic resonance (FMR) spectra and a shift of the resonant magnetic field. We further find experimentally that the spin-pumping-induced contribution to the linewidth is inversely proportional to the thickness of the Py layer. We show that this thickness dependence likely originates from the dissipative dynamics of the free and localized spins in the AFM layer. The results obtained could be used for tailoring the dissipative properties of spintronic devices incorporating antiferromagnetic layers.
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| 2. |
- Polishchuk, Dmytr, et al.
(author)
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Isotropic FMR frequency enhancement in thin Py/FeMn bilayers under strong magnetic proximity effect
- 2021
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In: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 54:30
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Journal article (peer-reviewed)abstract
- Exchange biasing in ferromagnet/antiferromagnet bilayers is known to enhance the material's ferromagnetic resonance frequency and make it strongly angle dependent due to the unidirectional anisotropy induced at the interface. We observe a ten-fold enhancement in frequency and angle-independent ferromagnetic resonance in bilayers of Py/FeMn with ultrathin FeMn, accompanied by a significantly enhanced magnetic moment. The observed isotropic frequency enhancement is consistent with rotatable rather than unidirectional magnetic anisotropy and the induced magnetic moment links this anisotropy with the ferromagnet-proximity effect. The estimated effective anisotropy field acting on the proximity-induced moment in ultrathin FeMn can be as high as 0.5 T at room temperature. Our results show the potential of the ferromagnetic proximity effect combined with the inherent exchange anisotropy in antiferromagnets for high-speed spintronic applications.
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| 3. |
- Polishchuk, Dmytro M., et al.
(author)
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Spin relaxation in multilayers with synthetic ferrimagnets
- 2018
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In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 98:14
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Journal article (peer-reviewed)abstract
- We demonstrate the strong tunability of the spin-pumping contribution to magnetic damping in a thin-film ferromagnetic free layer interfacing with a synthetic ferrimagnet (SFM), acting as a spin sink, via a thin Cu spacer. The effect strongly depends on the magnetic state of the SFM, a trilayer structure composed of two Fe layers coupled via indirect exchange mediated by a Cr spacer. With increasing Cr thickness, the SFM state undergoes a transition from an antiparallel configuration via a noncollinear configuration to a parallel configuration. We can explain the corresponding nonmonotonous dependence of spin relaxation in the free layer in terms of modulation of the longitudinal spin transport as well as relaxation of the transverse angular momentum in the SFM. The results should be useful for designing high-speed spintronic devices where tunability of spin relaxation is advantageous.
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| 4. |
- Polishchuk, Dmytr, et al.
(author)
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Spin-current dissipation in a thin-film bilayer ferromagnet/antiferromagnet
- 2020
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In: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 46:8, s. 813-819
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Journal article (peer-reviewed)abstract
- Ferromagnetic resonance in multilayer metal nanostructures containing an antiferromagnetic layer of variable thickness is studied. The contribution to the linewidth of the ferromagnetic resonance that is caused by spin-pumping current dissipation in an exchange-coupled antiferromagnetic/ferromagnetic bilayer is determined. The dissipative processes that occur in the bulk of the antiferromagnet and at the interface between the antiferromagnet (Fe50Mn50) and the ferromagnet (permalloy, Ni81Fe19) are distinguished. The details of how the dissipation transforms when the antiferromagnet Neel vector deviates from the direction of the exchange-pinning field are determined. The proposed method is effective for studying spin scattering in individual layers and at interlayer interfaces in complex magnetic systems.
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| 5. |
- Tykhonenko-Polishchuk, Yuliya, et al.
(author)
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Spin-dependent scattering and magnetic proximity effect in Ni-doped Co/Cu multilayers as a probe of atomic magnetism
- 2019
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 125:2
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Journal article (peer-reviewed)abstract
- We investigate the spin transport and ferromagnetic resonance properties of giant magnetoresistance (GMR) Co/Cu-Ni multilayers with variable levels of Ni doping in the Cu spacer. We present an experimental evidence for a magnetic-to-diamagnetic transition in the atomic magnetic moment of Ni in the Cu matrix for concentrations below 15 at. % Ni. As its concentration is increased, Ni atoms turn into spin scattering centers, which is manifested experimentally as a step-like change in the GMR of the multilayers. This behavior is observed in multilayers with gradient-doped Cu spacers, where only the inner region was doped with Ni. In the uniformly doped spacers, the GMR decreases monotonously with increasing Ni content, indicating that Ni atoms are magnetic and act as spin relaxation centers in the entire dopant-concentration range studied. We explain the difference in the observed GMR behavior due to a strong magnetic proximity effect in the uniform spacers, which is efficiently suppressed in the gradient spacers. The observed magnetic phase transition is fully supported by our detailed ab initio calculations, taking into consideration structural relaxation in the system as well as potential Ni clustering. Controlling the loss or gain of the atomic magnetism for a specific dopant can be a tool in probing and controlling spin relaxation in materials and devices for spin-valve and spin-torque based applications.
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| 6. |
- Polishchuk, Dmytr, et al.
(author)
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Angle resolved relaxation of spin currents by antiferromagnets in spin valves
- 2019
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:24
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Journal article (peer-reviewed)abstract
- We observe and analyze tunable relaxation of a pure spin current by an antiferromagnet in spin valves. This is achieved by carefully controlling the angle between a resonantly excited ferromagnetic layer pumping the spin current and the Neel vector of the antiferromagnetic layer. The effect is observed as an angle-dependent spin-pumping contribution to the ferromagnetic resonance linewidth. An interplay between spin-mixing conductance and, often disregarded, longitudinal spin conductance is found to underlie our observations, which is in agreement with a recent prediction for related ferromagnetic spin valves.
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