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Arun R, Gopal R, Chandrasekar VK, Lakshmanan M. Exploration of field-like torque and field-angle tunability in coupled spin-torque nano oscillators for synchronization. CHAOS (WOODBURY, N.Y.) 2024; 34:013114. [PMID: 38198682 DOI: 10.1063/5.0173943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024]
Abstract
We investigate the influence of field-like torque and the direction of the external magnetic field on a one-dimensional array of serially connected spin-torque nano oscillators (STNOs), having free layers with perpendicular anisotropy, to achieve complete synchronization between them by analyzing the associated Landau-Lifshitz-Gilbert-Slonczewski equation. The obtained results for synchronization are discussed for the cases of 2, 10, and 100 oscillators separately. The roles of the field-like torque and the direction of the external field on the synchronization of the STNOs are explored through the Kuramoto order parameter. While the field-like torque alone is sufficient to bring out global synchronization in the system made up of a small number of STNOs, the direction of the external field is also needed to be slightly tuned to synchronize the one-dimensional array of a large number of STNOs. The formation of complete synchronization through the construction of clusters within the system is identified for the 100 oscillators. The large amplitude synchronized oscillations are obtained for small to large numbers of oscillators. Moreover, the tunability in frequency for a wide range of currents is shown for the synchronized oscillations up to 100 spin-torque oscillators. In addition to achieving synchronization, the field-like torque increases the frequency of the synchronized oscillations. The transverse Lyapunov exponents are deduced to confirm the stable synchronization in coupled STNOs due to the field-like torque and to validate the results obtained in the numerical simulations. The output power of the array is estimated to be enhanced substantially due to complete synchronization by the combined effect of field-like torque and tunability of the field-angle.
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Affiliation(s)
- R Arun
- Department of Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirapalli 620024, India
| | - R Gopal
- Department of Physics, Centre for Nonlinear Science & Engineering, School of Electrical & Electronics Engineering, SASTRA Deemed University, Thanjavur 613 401, India
| | - V K Chandrasekar
- Department of Physics, Centre for Nonlinear Science & Engineering, School of Electrical & Electronics Engineering, SASTRA Deemed University, Thanjavur 613 401, India
| | - M Lakshmanan
- Department of Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirapalli 620024, India
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2
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Zhu K, Carpentieri M, Zhang L, Fang B, Cai J, Verba R, Giordano A, Puliafito V, Zhang B, Finocchio G, Zeng Z. Nonlinear amplification of microwave signals in spin-torque oscillators. Nat Commun 2023; 14:2183. [PMID: 37069148 PMCID: PMC10110546 DOI: 10.1038/s41467-023-37916-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 04/05/2023] [Indexed: 04/19/2023] Open
Abstract
Spintronics-based microwave devices, such as oscillators and detectors, have been the subject of intensive investigation in recent years owing to the potential reductions in size and power consumption. However, only a few concepts for spintronic amplifiers have been proposed, typically requiring complex device configurations or material stacks. Here, we demonstrate a spintronic amplifier based on two-terminal magnetic tunnel junctions (MTJs) produced with CMOS-compatible material stacks that have already been used for spin-transfer torque memories. We achieve a record gain (|S11 | > 2) for input power on the order of nW (<-40 dBm) at an appropriate choice of the bias field direction and amplitude. Based on micromagnetic simulations and experiments, we describe the fundamental aspects driving the amplification and show the key role of the co-existence in microwave emissions of a dynamic state of the MTJ excited by a dc current and the injection locking mode driven by the microwave input signal. Our work provides a way to develop a class of compact amplifiers that can impact the design of the next generation of spintronics-CMOS hybrid systems.
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Affiliation(s)
- Keqiang Zhu
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, Bari, Italy
| | - Like Zhang
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China
- School of Electronics and Information Engineering, Wuxi University, Wuxi, Jiangsu, China
| | - Bin Fang
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China.
| | - Jialin Cai
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | | | - Anna Giordano
- Department of Engineering, University of Messina, Messina, Italy
| | - Vito Puliafito
- Department of Electrical and Information Engineering, Politecnico di Bari, Bari, Italy
| | - Baoshun Zhang
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy.
| | - Zhongming Zeng
- Nanofabrication facility, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu, China.
- Division of Nano-Devices and Technologies & Nanchang Key Laboratory of Advanced Packaging, Jiangxi Institute of Nanotechnology, Nanchang, China.
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3
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Litvinenko A, Sidi El Valli A, Iurchuk V, Louis S, Tyberkevych V, Dieny B, Slavin AN, Ebels U. Ultrafast GHz-Range Swept-Tuned Spectrum Analyzer with 20 ns Temporal Resolution Based on a Spin-Torque Nano-Oscillator with a Uniformly Magnetized "Free" Layer. NANO LETTERS 2022; 22:1874-1879. [PMID: 35167307 DOI: 10.1021/acs.nanolett.1c04031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The advantage of an ultrafast frequency-tunability of spin-torque nano-oscillators (STNOs) that have a large (>100 MHz) relaxation frequency of amplitude fluctuations is exploited to realize ultrafast wide-band time-resolved spectral analysis at nanosecond time scale with a frequency resolution limited only by the "bandwidth" theorem. The demonstration is performed with an STNO generating in the 9 GHz frequency range and comprised of a perpendicular polarizer and a perpendicularly and uniformly magnetized "free" layer. It is shown that such a uniform-state STNO-based spectrum analyzer can efficiently perform spectral analysis of frequency-agile signals with rapidly varying frequency components.
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Affiliation(s)
- Artem Litvinenko
- Université Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | | | - Vadym Iurchuk
- Université Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Steven Louis
- Oakland University, Rochester, Michigan 48309, United States
| | | | - Bernard Dieny
- Université Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Andrei N Slavin
- Oakland University, Rochester, Michigan 48309, United States
| | - Ursula Ebels
- Université Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
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4
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Rana B, Mondal AK, Bandyopadhyay S, Barman A. Applications of nanomagnets as dynamical systems: I. NANOTECHNOLOGY 2021; 33:062007. [PMID: 34633310 DOI: 10.1088/1361-6528/ac2e75] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
When magnets are fashioned into nanoscale elements, they exhibit a wide variety of phenomena replete with rich physics and the lure of tantalizing applications. In this topical review, we discuss some of these phenomena, especially those that have come to light recently, and highlight their potential applications. We emphasize what drives a phenomenon, what undergirds the dynamics of the system that exhibits the phenomenon, how the dynamics can be manipulated, and what specific features can be harnessed for technological advances. For the sake of balance, we point out both advantages and shortcomings of nanomagnet based devices and systems predicated on the phenomena we discuss. Where possible, we chart out paths for future investigations that can shed new light on an intriguing phenomenon and/or facilitate both traditional and non-traditional applications.
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Affiliation(s)
- Bivas Rana
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University in Poznań, Uniwersytetu Poznanskiego 2, Poznań 61-614, Poland
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Amrit Kumar Mondal
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Supriyo Bandyopadhyay
- Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, VA, 23284, United States of America
| | - Anjan Barman
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
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Li R, Yu Z, Zhang Z, Shao Y, Wang X, Finocchio G, Lu Z, Xiong R, Zeng Z. Spin hall nano-oscillators based on two-dimensional Fe 3GeTe 2 magnetic materials. NANOSCALE 2020; 12:22808-22816. [PMID: 33174554 DOI: 10.1039/d0nr06449a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Two-dimensional (2D) magnetic materials with high perpendicular anisotropy, such as Fe3GeTe2, have the potential to build spintronic devices with better performance and lower power consumption. Here, we examine microwave emissions in Fe3GeTe2/Pt spin Hall nano-oscillators with different numbers of layers of Fe3GeTe2 using micromagnetic simulations. We predict that auto-oscillation with a frequency of >30 GHz can be driven by spin-orbit torque (SOT) and the frequency is tunable with current. Observing the dynamic behaviors of magnetization dynamic reveals that non-localized spin-wave propagates in Fe3GeTe2 with a spatially varied wavelength due to Joule heat and forms certain special bubble-like magnetic structure. Our results indicate SHNOs comprising a 2D magnetic material has the potential to develop future spintronic oscillator with low power consumption and high performance.
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Affiliation(s)
- Rongxin Li
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, P. R. China.
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Litvinenko A, Iurchuk V, Sethi P, Louis S, Tyberkevych V, Li J, Jenkins A, Ferreira R, Dieny B, Slavin A, Ebels U. Ultrafast Sweep-Tuned Spectrum Analyzer with Temporal Resolution Based on a Spin-Torque Nano-Oscillator. NANO LETTERS 2020; 20:6104-6111. [PMID: 32677836 DOI: 10.1021/acs.nanolett.0c02195] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We demonstrate that a spin-torque nano-oscillator (STNO) rapidly sweep-tuned by a bias voltage can be used to perform an ultrafast time-resolved spectral analysis of frequency-manipulated microwave signals. The critical reduction in the time of the spectral analysis comes from the naturally small-time constants of a nanosized STNO (1-100 ns). The demonstration is performed on a vortex-state STNO generating in a frequency range around 300 MHz, when frequency down-conversion and matched filtering is used for signal processing. It is shown that this STNO-based spectrum analyzer can perform analysis of frequency-agile signals, having multiple rapidly changing frequency components with temporal resolution in a μs time scale and frequency resolution limited only by the "bandwidth" theorem. Our calculations show that using uniform magnetization state STNOs it would be possible to increase the operating frequency of a spectrum analyzer to tens of GHz.
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Affiliation(s)
- Artem Litvinenko
- Univ. Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Vadym Iurchuk
- Univ. Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Pankaj Sethi
- Univ. Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Steven Louis
- Oakland University, 48309 Rochester Michigan United States
| | | | - Jia Li
- Oakland University, 48309 Rochester Michigan United States
| | - Alex Jenkins
- International Iberian Nanotechnology Laboratory (INL), 4715-330 Braga, Portugal
| | - Ricardo Ferreira
- International Iberian Nanotechnology Laboratory (INL), 4715-330 Braga, Portugal
| | - Bernard Dieny
- Univ. Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
| | - Andrei Slavin
- Oakland University, 48309 Rochester Michigan United States
| | - Ursula Ebels
- Univ. Grenoble Alpes, CEA, CNRS, Spintec, 38000 Grenoble, France
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7
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Zhang L, Fang B, Cai J, Wu W, Zhang B, Wang B, Amiri PK, Finocchio G, Zeng Z. Enhanced Broad-band Radio Frequency Detection in Nanoscale Magnetic Tunnel Junction by Interface Engineering. ACS APPLIED MATERIALS & INTERFACES 2019; 11:29382-29387. [PMID: 31342742 DOI: 10.1021/acsami.9b06706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Broad-band radio frequency (RF) detection is of great interest for its potential applications in wireless charging and energy harvesting. Here, we demonstrate that the bandwidth of broad-band RF detection in spin-torque diodes based on magnetic tunnel junctions (MTJs) can be enhanced through engineering the interface perpendicular magnetic anisotropy (PMA) between the CoFeB free layer and the MgO tunnel barrier. An ultrawide RF detection bandwidth of over 3 GHz is observed in the MTJs, and the broad-band RF detection behavior can be modulated by tuning the free layer PMA. Furthermore, a wide RF detection bandwidth (about 1.8 GHz) can be realized even without any external bias field for free layers with a thickness of about 1.65 nm. Finally, the dependence of the broad-band RF detection bandwidth on external magnetic field and RF power is discussed. Our results pave the way for RF energy harvesting for future portable nanoelectronics.
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Affiliation(s)
- Like Zhang
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
- School of Nano Technology and Nano Bionics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Bin Fang
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
| | - Jialin Cai
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
- School of Nano Technology and Nano Bionics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Weican Wu
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
| | - Baoshun Zhang
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
- School of Nano Technology and Nano Bionics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
| | - Bochong Wang
- Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science , Yanshan University , Qinhuangdao 066004 , People's Republic of China
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering , Northwestern University , Evanston , Illinois 60208 , United States
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences , University of Messina , Messina 98166 , Italy
| | - Zhongming Zeng
- Key Laboratory of Multifunctional Nanomaterials and Smart Systems , Suzhou Institute of Nano-Tech and Nano-Bionics, CAS , Suzhou , Jiangsu 215123 , People's Republic of China
- School of Nano Technology and Nano Bionics , University of Science and Technology of China , Hefei , Anhui 230026 , People's Republic of China
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8
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Tunnel magnetoresistance angular and bias dependence enabling tuneable wireless communication. Sci Rep 2019; 9:9541. [PMID: 31266999 PMCID: PMC6606570 DOI: 10.1038/s41598-019-45984-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 06/20/2019] [Indexed: 11/09/2022] Open
Abstract
Spin-transfer torques (STTs) can be exploited in order to manipulate the magnetic moments of nanomagnets, thus allowing for new consumer-oriented devices to be designed. Of particular interest here are tuneable radio-frequency (RF) oscillators for wireless communication. Currently, the structure that maximizes the output power is an Fe/MgO/Fe-type magnetic tunnel junction (MTJ) with a fixed layer magnetized in the plane of the layers and a free layer magnetized perpendicular to the plane. This structure allows for most of the tunnel magnetoresistance (TMR) to be converted into output power. Here, we experimentally and theoretically demonstrate that the main mechanism sustaining steady-state precession in such structures is the angular dependence of the magnetoresistance. The TMR of such devices is known to exhibit a broken-linear dependence versus the applied bias. Our results show that the TMR bias dependence effectively quenches spin-transfer-driven precession and introduces a non-monotonic frequency dependence at high applied currents. This has an impact on devices seeking to work in the 'THz gap' due to their non-trivial TMR bias dependences.
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Zhang Z, Liu E, Zhang W, Wong PKJ, Xu Z, Hu F, Li X, Tang J, Wee ATS, Xu F. Mechanical Strain Manipulation of Exchange Bias Field and Spin Dynamics in FeCo/IrMn Multilayers Grown on Flexible Substrates. ACS APPLIED MATERIALS & INTERFACES 2019; 11:8258-8265. [PMID: 30697995 DOI: 10.1021/acsami.8b21421] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
As a key effect in spintronic devices, exchange bias has attracted tremendous attention. Various approaches have been attempted for optimizing this effect, among which the application of strain in flexible exchange-biased systems is promising, but little significant improvement has been reported. Here, we demonstrate encouraging progress in this field. With a pure mechanical compressive strain of -6.26‰ applied to the flexible polyimide (PI) substrate, distinct enhancement of ∼900% in the bias field (from 20 to 200 Oe) is achieved for the exchange-biased (FeCo/IrMn)3/Ta multilayers grown on top of a flexible PI substrate, accompanied by a notable decrease in the Gilbert damping parameter from 0.02 to 0.008, signifying an improved exchange bias effect as well as a potentially reduced switching current density. The underlying mechanism is investigated by a systematic ferromagnetic resonance study, suggesting that the angle between the unidirectional and uniaxial magnetic easy axes plays an important role, which may be controlled by adjusting the layer number. This work offers an efficient strategy for tuning the exchange bias effect via applying appropriate mechanical strain on a multiperiodic exchange bias multilayered system, opening up an avenue for tailoring the magnetic properties of flexible spintronic devices.
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Affiliation(s)
- Zhi Zhang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Er Liu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Wen Zhang
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
| | - Ping Kwan Johnny Wong
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Zhan Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Fang Hu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Xia Li
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Jiaxuan Tang
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Andrew Thye Shen Wee
- Department of Physics , National University of Singapore , 2 Science Drive 3 , Singapore 117542 , Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre , National University of Singapore , 6 Science Drive 2 , Singapore 117546 , Singapore
| | - Feng Xu
- MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, School of Materials Science and Engineering , Nanjing University of Science and Technology , Nanjing 210094 , China
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10
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High power and low critical current density spin transfer torque nano-oscillators using MgO barriers with intermediate thickness. Sci Rep 2017; 7:7237. [PMID: 28775263 PMCID: PMC5543117 DOI: 10.1038/s41598-017-07762-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/03/2017] [Indexed: 12/03/2022] Open
Abstract
Reported steady-state microwave emission in magnetic tunnel junction (MTJ)-based spin transfer torque nano-oscillators (STNOs) relies mostly on very thin insulating barriers [resulting in a resistance × area product (R × A) of ~1 Ωμm2] that can sustain large current densities and thus trigger large orbit magnetic dynamics. Apart from the low R × A requirement, the role of the tunnel barrier in the dynamics has so far been largely overlooked, in comparison to the magnetic configuration of STNOs. In this report, STNOs with an in-plane magnetized homogeneous free layer configuration are used to probe the role of the tunnel barrier in the dynamics. In this type of STNOs, the RF modes are in the GHz region with integrated matched output powers (Pout) in the range of 1–40 nW. Here, Pout values up to 200 nW are reported using thicker insulating barriers for junctions with R × A values ranging from 7.5 to 12.5 Ωμm2, without compromising the ability to trigger self-sustained oscillations and without any noticeable degradation of the signal linewidth (Γ). Furthermore, a decrease of two orders of magnitude in the critical current density for spin transfer torque induced dynamics (JSTT) was observed, without any further change in the magnetic configuration.
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11
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Gou P, Qian J, Xi F, Zou Y, Cao J, Yu H, Zhao Z, Yang L, Xu J, Wang H, Zhang L, An Z. Dramatically Enhanced Spin Dynamo with Plasmonic Diabolo Cavity. Sci Rep 2017; 7:5332. [PMID: 28706290 PMCID: PMC5509722 DOI: 10.1038/s41598-017-05634-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 05/31/2017] [Indexed: 11/08/2022] Open
Abstract
The applications of spin dynamos, which could potentially power complex nanoscopic devices, have so far been limited owing to their extremely low energy conversion efficiencies. Here, we present a unique plasmonic diabolo cavity (PDC) that dramatically improves the spin rectification signal (enhancement of more than three orders of magnitude) under microwave excitation; further, it enables an energy conversion efficiency of up to ~0.69 mV/mW, compared with ~0.27 μV/mW without a PDC. This remarkable improvement arises from the simultaneous enhancement of the microwave electric field (~13-fold) and the magnetic field (~195-fold), which cooperate in the spin precession process generates photovoltage (PV) efficiently under ferromagnetic resonance (FMR) conditions. The interplay of the microwave electromagnetic resonance and the ferromagnetic resonance originates from a hybridized mode based on the plasmonic resonance of the diabolo structure and Fabry-Perot-like modes in the PDC. Our work sheds light on how more efficient spin dynamo devices for practical applications could be realized and paves the way for future studies utilizing both artificial and natural magnetism for applications in many disciplines, such as for the design of future efficient wireless energy conversion devices, high frequent resonant spintronic devices, and magnonic metamaterials.
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Affiliation(s)
- Peng Gou
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jie Qian
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Fuchun Xi
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yuexin Zou
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jun Cao
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Haochi Yu
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Ziyi Zhao
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Le Yang
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jie Xu
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Hengliang Wang
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Lijian Zhang
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China
| | - Zhenghua An
- State Key Laboratory of Surface Physics and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai, 200433, China.
- Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai, 200433, China.
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12
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Bran C, Ivanov YP, Kosel J, Chubykalo-Fesenko O, Vazquez M. Co/Au multisegmented nanowires: a 3D array of magnetostatically coupled nanopillars. NANOTECHNOLOGY 2017; 28:095709. [PMID: 28139469 DOI: 10.1088/1361-6528/aa585f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Arrays of multisegmented Co/Au nanowires with designed segment lengths and diameters have been prepared by electrodeposition into aluminum oxide templates. The high quality of the Co/Au interface and the crystallographic structure of Co segments have determined by high-resolution transmission electron microscopy. Magnetic hysteresis loop measurements show larger coercivity and squareness of multisegmented nanowires as compared to single segment Co nanowires. The complementary micromagnetic simulations are in good agreement with the experimental results, confirming that the magnetic behavior is defined mainly by magnetostatic coupling between different segments. The proposed structure constitutes an innovative route towards a 3D array of synchronized magnetic nano-oscillators with large potential in nanoelectronics.
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Affiliation(s)
- C Bran
- Institute of Materials Science of Madrid, CSIC, E-28049 Madrid, Spain
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Albert M, Beg M, Chernyshenko D, Bisotti MA, Carey RL, Fangohr H, Metaxas PJ. Frequency-based nanoparticle sensing over large field ranges using the ferromagnetic resonances of a magnetic nanodisc. NANOTECHNOLOGY 2016; 27:455502. [PMID: 27710921 DOI: 10.1088/0957-4484/27/45/455502] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using finite element micromagnetic simulations, we study how resonant magnetisation dynamics in thin magnetic discs with perpendicular anisotropy are influenced by magnetostatic coupling to a magnetic nanoparticle. We identify resonant modes within the disc using direct magnetic eigenmode calculations and study how their frequencies and spatial profiles are changed by the nanoparticle's stray magnetic field. We demonstrate that particles can generate shifts in the resonant frequency of the disc's fundamental mode which exceed resonance linewidths in recently studied spin torque oscillator devices. Importantly, it is shown that the simulated shifts can be maintained over large field ranges (here up to 1 T). This is because the resonant dynamics (the basis of nanoparticle detection here) respond directly to the nanoparticle stray field, i.e. detection does not rely on nanoparticle-induced changes to the magnetic ground state of the disc. A consequence of this is that in the case of small disc-particle separations, sensitivities to the particle are highly mode- and particle-position-dependent, with frequency shifts being maximised when the intense stray field localised directly beneath the particle can act on a large proportion of the disc's spins that are undergoing high amplitude precession.
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Affiliation(s)
- Maximilian Albert
- Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK
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14
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Liu Y, Zhang J, Wang S, Jiang S, Liu Q, Li X, Wu Z, Yu G. Ru Catalyst-Induced Perpendicular Magnetic Anisotropy in MgO/CoFeB/Ta/MgO Multilayered Films. ACS APPLIED MATERIALS & INTERFACES 2015; 7:26643-26648. [PMID: 26565747 DOI: 10.1021/acsami.5b08385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The high oxygen storage/release capability of the catalyst Ru is used to manipulate the interfacial electronic structure in spintronic materials to obtain perpendicular magnetic anisotropy (PMA). Insertion of an ultrathin Ru layer between the CoFeB and Ta layers in MgO/CoFeB/Ta/MgO films effectively induces PMA without annealing. Ru plays a catalytic role in Fe-O-Ta bonding and isolation at the metal-oxide interface to achieve moderate interface oxidation. In contrast, PMA cannot be obtained in the sample with a Mg insertion layer or without an insertion layer because of the lack of a catalyst. Our work would provide a new approach toward catalyst-induced PMA for future CoFeB-based spintronic device applications.
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Affiliation(s)
- Yiwei Liu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Jingyan Zhang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Shouguo Wang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Shaolong Jiang
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Qianqian Liu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Xujing Li
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
| | - Zhenglong Wu
- Analytical and Testing Center, Beijing Normal University , Beijing 100875, China
| | - Guanghua Yu
- Department of Materials Physics and Chemistry, University of Science and Technology Beijing , Beijing 100083, China
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15
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Zhu W, Xiao D, Liu Y, Gong SJ, Duan CG. Picosecond electric field pulse induced coherent magnetic switching in MgO/FePt/Pt(001)-based tunnel junctions: a multiscale study. Sci Rep 2014; 4:4117. [PMID: 24844293 PMCID: PMC4027858 DOI: 10.1038/srep04117] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 01/29/2014] [Indexed: 12/03/2022] Open
Abstract
Combined methods of first-principles calculations and Landau-Lifshitz-Gilbert (LLG) macrospin simulations are performed to investigate the coherent magnetization switching in the MgO/FePt/Pt(001)-based magnetic tunnel junctions triggered by short pulses of electric field through the control of magnetic anisotropy energy (MAE) electrically. First-principles calculations indicate that the MAE of MgO/FePt/Pt(001) film varies linearly with the change of the electric field, whereas the LLG simulations show that the change in MAE by electric field pulses could induce the in-plane magnetization reversal of the free layer by tuning the pulse parameters. We find that there exist a critical pulse width τmin to switch the in-plane magnetization, and this τmin deceases with the increasing pulse amplitude E0. Besides, the magnetization orientation cannot be switched when the pulse width exceeds a critical value τmax, and τmax increases asymptotically with E0. In addition, there exist some irregular switching areas at short pulse width due to the high precessional frequency under small initial angle. Finally, a successive magnetization switching can be achieved by a series of electric field pulses.
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Affiliation(s)
- Wanjiao Zhu
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, China
| | - Dun Xiao
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physical Science and Engineering, Tongji University, Shanghai 200092, China
| | - Yaowen Liu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physical Science and Engineering, Tongji University, Shanghai 200092, China
| | - S J Gong
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, China
| | - Chun-Gang Duan
- 1] Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, China [2] National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai 200083, China
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16
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Pikovsky A. Robust synchronization of spin-torque oscillators with an LCR load. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:032812. [PMID: 24125317 DOI: 10.1103/physreve.88.032812] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Indexed: 06/02/2023]
Abstract
We study dynamics of a serial array of spin-torque oscillators with a parallel inductor-capacitor-resistor (LCR) load. In a large range of parameters the fully synchronous regime, where all the oscillators have the same state and the output field is maximal, is shown to be stable. However, not always such a robust complete synchronization develops from a random initial state; in many cases nontrivial clustering is observed, with a partial synchronization resulting in a quasiperiodic or chaotic mean-field dynamics.
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Affiliation(s)
- Arkady Pikovsky
- Department of Physics and Astronomy, Potsdam University, Karl-Liebknecht-Str 24, D-14476, Potsdam, Germany and NEXT, Laboratoire de Physique Théorique du CNRS, IRSAMC, Université Toulouse, UPS, 31062 Toulouse, France
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17
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Rowlands GE, Katine JA, Langer J, Zhu J, Krivorotov IN. Time domain mapping of spin torque oscillator effective energy. PHYSICAL REVIEW LETTERS 2013; 111:087206. [PMID: 24010473 DOI: 10.1103/physrevlett.111.087206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Indexed: 06/02/2023]
Abstract
Stochastic dynamics of spin torque oscillators can be described in terms of magnetization drift and diffusion over a current-dependent effective energy surface given by the Fokker-Planck equation. Here we present a method that directly probes this effective energy surface via time-resolved measurements of the microwave voltage generated by a spin torque oscillator. We show that the effective energy approach provides a simple recipe for predicting spectral linewidths and line shapes near the generation threshold. Our time domain technique also accurately measures the fieldlike component of spin torque in a wide range of the voltage bias values.
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Affiliation(s)
- Graham E Rowlands
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
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18
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Abstract
The use of spin transfer nano-oscillators (STNOs) to generate microwave signals in nanoscale devices has aroused tremendous and continuous research interest in recent years. Their key features are frequency tunability, nanoscale size, broad working temperature, and easy integration with standard silicon technology. In this feature article, we give an overview of recent developments and breakthroughs in the materials, geometry design and properties of STNOs. We focus in more depth on our latest advances in STNOs with perpendicular anisotropy, showing a way to improve the output power of STNO towards the μW range. Challenges and perspectives of the STNOs that might be productive topics for future research are also briefly discussed.
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Affiliation(s)
- Zhongming Zeng
- Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, P. R. China.
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Ultralow-current-density and bias-field-free spin-transfer nano-oscillator. Sci Rep 2013; 3:1426. [PMID: 23478390 PMCID: PMC3594754 DOI: 10.1038/srep01426] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 02/19/2013] [Indexed: 12/03/2022] Open
Abstract
The spin-transfer nano-oscillator (STNO) offers the possibility of using the transfer of spin angular momentum via spin-polarized currents to generate microwave signals. However, at present STNO microwave emission mainly relies on both large drive currents and external magnetic fields. These issues hinder the implementation of STNOs for practical applications in terms of power dissipation and size. Here, we report microwave measurements on STNOs built with MgO-based magnetic tunnel junctions having a planar polarizer and a perpendicular free layer, where microwave emission with large output power, excited at ultralow current densities, and in the absence of any bias magnetic fields is observed. The measured critical current density is over one order of magnitude smaller than previously reported. These results suggest the possibility of improved integration of STNOs with complementary metal-oxide-semiconductor technology, and could represent a new route for the development of the next-generation of on-chip oscillators.
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