| 1. |
- Chowdhury, N., et al.
(författare)
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Kagome Magnets: The Emerging Materials for Spintronic Memories
- 2023
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Ingår i: Proceedings of the National Academy of Sciences India Section a-Physical Sciences. - 0369-8203. ; 93, s. 477-495
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Forskningsöversikt (refereegranskat)abstract
- Recent developments in the field of topological quantum materials have stimulated the search for materials that could serve as the building blocks for next-generation memory applications. Due to their intriguing topological properties, such as flat bands, Dirac nodes, and Weyl points, kagome magnets are anticipated to be the leading materials for this application. In this mini review, we discuss some of the recent advancements in binary kagome magnets, both ferromagnetic and anti-ferromagnetic, for use as emerging memory devices. First, we discuss ferromagnetic kagome magnets, specifically Fe3Sn2, and then we discuss non-collinear antiferromagnetic kagome magnets, Mn3Sn and Mn3Ir. Finally, we discuss collinear antiferromagnetic kagome magnet, FeSn. In each of the aforementioned sections, we begin with a discussion of their topological, structural, and magnetic properties, followed by application-specific studies such as spin-orbit torques (SOT). In the final section, we discuss the current state of kagome magnets for efficient, faster, denser, and reliable memory technologies with focus on the SOT switching and observation/manipulation of skyrmions.
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| 2. |
- Kumar, Akash, et al.
(författare)
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Interfacial Origin of Unconventional Spin-Orbit Torque in Py/r-IrMn3
- 2023
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Ingår i: Advanced Quantum Technologies. - 2511-9044. ; 6:7
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Tidskriftsartikel (refereegranskat)abstract
- Angle-resolved spin-torque ferromagnetic resonance measurements are carried out in heterostructures consisting of Py (Ni81Fe19) and a noncollinear antiferromagnetic quantum material r-IrMn3. The structural characterization reveals that r-IrMn3 is polycrystalline in nature. A large exchange bias of 158 Oe is found in Py/r-IrMn3 at room temperature, while r-IrMn3/Py and Py/Cu/r-IrMn3 exhibit no exchange bias. Regardless of the exchange bias and stacking sequence, a substantial unconventional out-of-plane anti-damping torque is observed when r-IrMn3 is in direct contact with Py. The magnitude of the out-of-plane spin-orbit torque efficiency is found to be twice as large as the in-plane spin-orbit torque efficiency. The unconventional spin-orbit torque vanishes when a Cu spacer is introduced between Py and r-IrMn3, indicating that the unconventional spin-orbit torque in this system originates at the interface. These findings are important for realizing efficient antiferromagnet-based spintronic devices via interfacial engineering.
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| 3. |
- Sharma, R., et al.
(författare)
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Modulation Rate Study in a Spin-Torque Oscillator-Based Wireless Communication System
- 2015
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Ingår i: IEEE transactions on magnetics. - : IEEE Press. - 0018-9464 .- 1941-0069. ; 51:11
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Tidskriftsartikel (refereegranskat)abstract
- We study a wireless communication system based on a magnetic tunnel junction spin-torque nano-oscillator (STNO) by employing amplitude-shift-keying modulation. By varying the pulse modulation frequency (f(m)) from 1 kHz to 2 MHz and distance (D) between the antenna from 25 to 150 cm, we show a maximum data rate of 6 Mb/s (at D = 25 cm and fm = 1 MHz), a limit imposed by our setup and noise generated by the STNO itself. We also report the average amplitude noise (S-delta a) and average white frequency noise (S-wh) of the wireless communication system and discuss their dependence on the distance between the antennas.
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| 4. |
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| 5. |
- Bangar, H., et al.
(författare)
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Large Spin Hall Conductivity in Epitaxial Thin Films of Kagome Antiferromagnet Mn3Sn at Room Temperature
- 2022
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Ingår i: Advanced Quantum Technologies. - : Wiley. - 2511-9044. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Mn3Sn is a non-collinear antiferromagnetic quantum material that exhibits a magnetic Weyl semimetallic state and has great potential for efficient memory devices. High-quality epitaxial c-plane Mn3Sn thin films have been grown on a sapphire substrate using a Ru seed layer. Using spin pumping induced inverse spin Hall effect measurements on c-plane epitaxial Mn3Sn/Ni80Fe20, spin-diffusion length (lambda(Mn3Sn)), and spin Hall conductivity (sigma(SH)) of Mn3Sn thin films are measured: lambda(Mn3Sn) = 0.42 +/- 0.04 nm and sigma(SH) = -702 h/e Omega(-1)cm(-1). While lambda(Mn3Sn) is consistent with earlier studies, sigma(SH) is an order of magnitude higher and of the opposite sign. The behavior is explained on the basis of excess Mn, which shifts the Fermi level in these films, leading to the observed behavior. These findings demonstrate a technique for engineering sigma(SH) of Mn3Sn films by employing Mn composition for functional spintronic devices.
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| 6. |
- Bangar, H., et al.
(författare)
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Large Spin-To-Charge Conversion at the Two-Dimensional Interface of Transition-Metal Dichalcogenides and Permalloy
- 2022
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 14:36, s. 41598-41604
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Tidskriftsartikel (refereegranskat)abstract
- Spin-to-charge conversion is an essential requirement for the implementation of spintronic devices. Recently, monolayers (MLs) of semiconducting transition-metal dichalcogenides (TMDs) have attracted considerable interest for spin-to-charge conversion due to their high spin-orbit coupling and lack of inversion symmetry in their crystal structure. However, reports of direct measurement of spin-to-charge conversion at TMD-based interfaces are very much limited. Here, we report on the room-temperature observation of a large spin-to-charge conversion arising from the interface of Ni80Fe20 (Py) and four distinct large-area (similar to 5 x 2 mm(2)) ML TMDs, namely, MoS2, MoSe2, WS2, and WSe2. We show that both spin mixing conductance and the Rashba efficiency parameter (lambda(IREE)) scale with the spin-orbit coupling strength of the ML TMD layers. The lambda(IREE) parameter is found to range between -0.54 and -0.76 nm for the four ML TMDs, demonstrating a large spin-to-charge conversion. Our findings reveal that the TMD/ferromagnet interface can be used for efficient generation and detection of spin current, opening new opportunities for novel spintronic devices.
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| 7. |
- Muduli, Pranaba, et al.
(författare)
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Composition dependent properties of Fe3Si films grown on GaAs(113)A substrates
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:7, s. 07B104-
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Tidskriftsartikel (refereegranskat)abstract
- Structural, electrical, and magnetic properties of Fe3Si/GaAs(113)A hybrid structures are studied, dependent on the layer composition varying from 15 to 26 at. % Si. The presence of superlattice reflections in x-ray diffraction and lower resistivity confirms the long-range atomic ordering in the stoichiometric Fe3Si films, reflecting the D0(3) crystal structure. The observed atomic ordering is also found to influence the sign and magnitude of the antisymmetric component of the planar Hall effect observed in this orientation. However a finite disorder is observed even in nearly stoichiometric samples.
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| 8. |
- Muduli, Pranaba K., et al.
(författare)
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Spin wave excitations in Fe films grown on GaAs(113)A substrates
- 2008
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 320:21, s. 2835-2838
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Tidskriftsartikel (refereegranskat)abstract
- The spin wave excitation and its size effect has been studied in Al- capped Fe. lms grown on lowsymmetry GaAs( 113) A substrates. The temperature dependence of saturation magnetization follows an effective Bloch's law as long as magnetization remains larger than about 70% of its saturation value. A signi. cant increase of the spin wave parameter B is found in Al- capped ultrathin Fe. lms grown on GaAs( 113) A compared to bulk Fe, Fe. lms on GaAs( 0 01) and other systems. This is explained as a result of the reduction in uniaxial magnetic anisotropy observed in this orientation for the same thickness range. However, this observed uniaxial magnetic anisotropy is found to be a likely reason for stabilizing the ferromagnetism.
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| 9. |
- Tiwari, D., et al.
(författare)
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Antidamping spin-orbit torques in epitaxial-Py(100)/beta-Ta
- 2017
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 111:23
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Tidskriftsartikel (refereegranskat)abstract
- We perform spin torque ferromagnetic resonance measurements on the Si(100)/TiN(100)/epi-Py(100)/beta-Ta system. We demonstrate current induced modulation of the Gilbert damping constant, which is about 30% for a current density of 6.25 x 10(9) A/m(2). We show that the observed modulation of the Gilbert damping constant cannot be explained by spin transfer torques arising from the spin Hall effect of the beta-Ta layer. An additional mechanism such as antidamping spinorbit torque resulting from the interface or the crystalline structure of Py thin films needs to be considered. Published by AIP Publishing.
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| 10. |
- Chen, Tingsu, et al.
(författare)
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Spin-Torque and Spin-Hall Nano-Oscillators
- 2016
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Ingår i: Proceedings of the IEEE. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9219 .- 1558-2256. ; 104:10, s. 1919-1945
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews the state of the art in spin-torque and spin-Hall-effect-driven nano-oscillators. After a brief introduction to the underlying physics, the authors discuss different implementations of these oscillators, their functional properties in terms of frequency range, output power, phase noise, and modulation rates, and their inherent propensity for mutual synchronization. Finally, the potential for these oscillators in a wide range of applications, from microwave signal sources and detectors to neuromorphic computation elements, is discussed together with the specific electronic circuitry that has so far been designed to harness this potential.
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