| 1. |
- Bainsla, Lakhan, et al.
(författare)
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Ultrathin Ferrimagnetic GdFeCo Films with Low Damping
- 2022
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 32:23, s. 2111693-
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Tidskriftsartikel (refereegranskat)abstract
- Ferromagnetic materials dominate as the magnetically active element in spintronic devices, but come with drawbacks such as large stray fields and low operational frequencies. Compensated ferrimagnets provide an alternative as they combine the ultrafast magnetization dynamics of antiferromagnets with a ferromagnet-like spin-orbit-torque behavior. However, to use ferrimagnets in spintronic devices their advantageous properties must be retained also in ultrathin films (t < 10 nm). In this study, ferrimagnetic Gdx(Fe87.5Co12.5)1−x thin films in the thickness range t = 2–20 nm are grown on high resistance Si(100) substrates and studied using broadband ferromagnetic resonance measurements at room temperature. By tuning their stoichiometry, a nearly compensated behavior is observed in 2 nm Gdx(Fe87.5Co12.5)1−x ultrathin films for the first time, with an effective magnetization of (Formula presented.) = 0.02 T and a low effective Gilbert damping constant of α = 0.0078, comparable to the lowest values reported so far in 30 nm films. These results show great promise for the development of ultrafast and energy efficient ferrimagnetic spintronic devices.
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| 2. |
- Behera, Nilamani, et al.
(författare)
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Energy-Efficient W100-xTax/ Co-Fe-B/MgO Spin Hall Nano-Oscillators
- 2022
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Ingår i: Physical Review Applied. - 2331-7019. ; 18:2
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a W-Ta alloying route to reduce the auto-oscillation threshold current densities and the power consumption of nanoconstriction based spin Hall nano-oscillators. Using spin-torque ferromagnetic resonance measurements on microbars of W100-xTax(5 nm)/Co-Fe-B(t)/MgO stacks with t=1.4, 1.8, and 2.0 nm, we measure a substantial improvement in both the spin-orbit torque efficiency and the spin Hall conductivity. We demonstrate a 34% reduction in auto-oscillation threshold current density, which translates into a 64% reduction in power consumption as compared with pure W-based spin Hall nano-oscillators. Our work demonstrates the promising aspects of W-Ta alloying for the energy-efficient operation of emerging spintronic devices.
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| 3. |
- Goyat, E., et al.
(författare)
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Large exchange bias and spin pumping in ultrathin IrMn/Co system for spintronic device applications
- 2022
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 588
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Tidskriftsartikel (refereegranskat)abstract
- Few nanometers thick antiferromagnetic/Ferromagnetic bilayer based spintronic devices have emerged as a potential nanostructured bilayer for achieving ultrahigh-speed magnetization switching, low power dissipation, terahertz magnetization dynamics, and are compatible with CMOS technology. The systematic investigation of the exchange bias (EB) in theIr(22)Mn(78)/Co system is performed by varying Co thickness (t(Co)) in the range of 6-20 nm with 10 nm thin Ir22Mn78 layer on top, using longitudinal magneto-optic Kerr effect (L-MOKE) and ferromagnetic resonance (FMR) measurements at room temperature. Here, we report the occurrence of a record high EB field in this bilayer system, which is 13.11 mT (9.04 mT) statically (dynamically) for 6 nm thick of Co. The percentage change of 313.5 % (251.7%) in exchange bias field is found through FMR (MOKE) measurements with respect to t(Co) variation from 20 to 6 nm. Additionally, the spin pumping mechanism is also studied in the above stated material system by using the FMR technique. The observed linear dependence of effective Gilbert's damping with respect to the 1/t(Co)& nbsp;, indicates the occurrence of spin pumping phenomena. The study suggests that tunability of both the exchange interaction and spin pumping behavior in this Ir22Mn78/Co system, makes this system suitable for future antiferromagnetic spintronic devices.
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| 4. |
- Husain, S., et al.
(författare)
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Large Dzyaloshinskii-Moriya interaction and atomic layer thickness dependence in a ferromagnet- WS2 heterostructure
- 2022
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 105:6
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional transition metal dichalcogenides (TMDs) have immense potential for spintronics applications. Here, we report atomic layer thickness dependence in WS2/Co3FeB heterostructures. The layer dependence is predicted by density functional theory and demonstrated experimentally by the layer dependence of the Dzyaloshinskii-Moriya interaction (DMI). Notably, we have observed the DMI in WS2 to be larger than that for heavy metals such as W and Ta, which is important to stabilize chiral structures. Inversion symmetry is not preserved with an odd number of layers, while it exists with an even number of layers. This symmetry rule is reflected in the temperature dependence of the effective damping parameter of the heterostructure. That the damping parameter decreases (increases) in odd (even) layers can be resolved at low temperature. This suggests that the layer dependence has its origin at the WS2 interface, where the spin-valley coupling and spin-orbit coupling activate these features. Large DMI, pure spin current, and unique layer dependence in TMDs provide valuable information and fundamental understanding for designing TMD-based quantum information storage devices. © 2022 American Physical Society.
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