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Kumar D, Chung HJ, Chan J, Jin T, Lim ST, Parkin SSP, Sbiaa R, Piramanayagam SN. Ultralow Energy Domain Wall Device for Spin-Based Neuromorphic Computing. ACS Nano 2023; 17:6261-6274. [PMID: 36944594 DOI: 10.1021/acsnano.2c09744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Neuromorphic computing (NC) is gaining wide acceptance as a potential technology to achieve low-power intelligent devices. To realize NC, researchers investigate various types of synthetic neurons and synaptic devices, such as memristors and spintronic devices. In comparison, spintronics-based neurons and synapses have potentially higher endurance. However, for realizing low-power devices, domain wall (DW) devices that show DW motion at low energies─typically below pJ/bit─are favored. Here, we demonstrate DW motion at current densities as low as 106 A/m2 by engineering the β-W spin-orbit coupling (SOC) material. With our design, we achieve ultralow pinning fields and current density reduction by a factor of 104. The energy required to move the DW by a distance of about 18.6 μm is 0.4 fJ, which translates into the energy consumption of 27 aJ/bit for a bit-length of 1 μm. With a meander DW device configuration, we have established a controlled DW motion for synapse applications and have shown the direction to make ultralow energy spin-based neuromorphic elements.
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Affiliation(s)
- Durgesh Kumar
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Hong Jing Chung
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore
| | - JianPeng Chan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Tianli Jin
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Sze Ter Lim
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, 138634, Singapore
| | - Stuart S P Parkin
- Max Planck Institute for Microstructure Physics, 06120 Halle, Germany
| | - Rachid Sbiaa
- Department of Physics, Sultan Qaboos University, P.O. Box 36, PC 123, Muscat, Oman
| | - S N Piramanayagam
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
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Kwon J, Hwang HK, Hong JI, You CY. Bidirectional propagation of tilting domain walls in perpendicularly magnetized T shaped structure with the interfacial Dzyaloshinskii-Moriya interaction. Sci Rep 2018; 8:18035. [PMID: 30575792 PMCID: PMC6303305 DOI: 10.1038/s41598-018-36523-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 11/21/2018] [Indexed: 11/17/2022] Open
Abstract
Understanding of domain wall (DW) propagation in a complex structure is an essential first step toward the development of any magnetic-domain based devices including spin-based logic or magnetic memristors. Interfacial Dzyaloshinskii-Moriya interaction (iDMI) in the structure with broken inversion symmetry induces an asymmetrical DW configuration with respect to the direction of in-plane field. Dynamic behaviors of field-driven DW within the film with perpendicular magnetic anisotropy is influenced by DW tilt from the iDMI effect and the corners in the T-shaped structure of the DW path. Images from Kerr microscopy reveal that the iDMI effective field contributes to a tilted structure of DW configuration and evolution along its propagation. With the combination of iDMI and T-shaped structure, we observed two distinguished bidirectional DW propagations in two output branches and distinct arriving times at the destination pads with a uniform external field. Micromagnetic simulation results is compared with the observed dynamics of a DW configuration in the structure providing an additional confirmation of the interpreted results.
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Affiliation(s)
- Jaesuk Kwon
- Department of Emerging Materials Science, DGIST, Daegu, 42988, South Korea
| | - Hee-Kyeong Hwang
- Department of Emerging Materials Science, DGIST, Daegu, 42988, South Korea
| | - Jung-Il Hong
- Department of Emerging Materials Science, DGIST, Daegu, 42988, South Korea.
| | - Chun-Yeol You
- Department of Emerging Materials Science, DGIST, Daegu, 42988, South Korea.
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Moon KW, Kim C, Yoon J, Choi JW, Kim DO, Song KM, Kim D, Chun BS, Hwang C. A spin torque meter with magnetic facet domains. Nat Commun 2018; 9:3788. [PMID: 30224700 PMCID: PMC6141574 DOI: 10.1038/s41467-018-06223-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 08/24/2018] [Indexed: 11/23/2022] Open
Abstract
Current-induced magnetic domain wall (DW) motion is an important operating principle of spintronic devices. Injected current generates spin torques (STs) on the DWs in two ways. One is the spin transfer from magnetic domains to the walls by the current flowing in the magnet. Current flow in attached heavy metals also generates another ST because of the spin-Hall effect. Both phenomena explain the wall motions well; therefore, their respective contribution is an important issue. Here, we show the simultaneous measurement of both torques by using magnetic facet domains that form mountain-shaped domains with straight walls. When the STs and the external magnetic field push the walls in opposite directions, the walls should have equilibrium angles to create balanced states. Such angles can be modulated by an additional in-plane magnetic field. Angle measurements distinguish the STs because each torque has a distinct mechanism related to the DW structure.
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Affiliation(s)
- Kyoung-Woong Moon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Changsoo Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jungbum Yoon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jun Woo Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Dong-Ok Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Soongsil University, Seoul, 06978, Republic of Korea
| | - Kyung Mee Song
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Sookmyung Women's University, Seoul, 04130, Republic of Korea
| | - Dongseuk Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Byong Sun Chun
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Chanyong Hwang
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea.
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Abstract
In this work we introduce an alternating magnetic field generator in a cylindrical nanostructure. This field appears due to the rotation of a magnetic domain wall located at some position, generating a magnetic region that varies its direction of magnetization alternately, thus inducing an alternating magnetic flux in its vicinity. This phenomenon occurs due to the competition between a spin-polarized current and a magnetic field, which allows to control both the angular velocity and the pinning position of the domain wall. As proof of concept, we study the particular case of a diameter-modulated nanowire with a spin-polarized current along its axis and the demagnetizing field produced by its modulation. This inhomogeneous field allows one to control the angular velocity of the domain wall as a function of its position along the nanowire allowing frequencies in the GHz range to be achieved. This generator could be used in telecommunications for devices in the range of radiofrequencies or, following Faraday's induction law, could also induce an electromotive force and be used as a movable alternate voltage source in future nanodevices.
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Zhang SF, Gan WL, Kwon J, Luo FL, Lim GJ, Wang JB, Lew WS. Highly Efficient Domain Walls Injection in Perpendicular Magnetic Anisotropy Nanowire. Sci Rep 2016; 6:24804. [PMID: 27098108 DOI: 10.1038/srep24804] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 04/06/2016] [Indexed: 11/09/2022] Open
Abstract
Electrical injection of magnetic domain walls in perpendicular magnetic anisotropy nanowire is crucial for data bit writing in domain wall-based magnetic memory and logic devices. Conventionally, the current pulse required to nucleate a domain wall is approximately ~1012 A/m2. Here, we demonstrate an energy efficient structure to inject domain walls. Under an applied electric potential, our proposed Π-shaped stripline generates a highly concentrated current distribution. This creates a highly localized magnetic field that quickly initiates the nucleation of a magnetic domain. The formation and motion of the resulting domain walls can then be electrically detected by means of Ta Hall bars across the nanowire. Our measurements show that the Π-shaped stripline can deterministically write a magnetic data bit in 15 ns even with a relatively low current density of 5.34 × 1011 A/m2. Micromagnetic simulations reveal the evolution of the domain nucleation – first, by the formation of a pair of magnetic bubbles, then followed by their rapid expansion into a single domain. Finally, we also demonstrate experimentally that our injection geometry can perform bit writing using only about 30% of the electrical energy as compared to a conventional injection line.
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Choi YH, Yoshimura Y, Kim KJ, Lee K, Kim TW, Ono T, You CY, Jung MH. Field-driven domain wall motion under a bias current in the creep and flow regimes in Pt/[CoSiB/Pt]N nanowires. Sci Rep 2016; 6:23933. [PMID: 27030379 PMCID: PMC4814914 DOI: 10.1038/srep23933] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/16/2016] [Indexed: 11/09/2022] Open
Abstract
The dynamics of magnetic domain wall (DW) in perpendicular magnetic anisotropy Pt/[CoSiB/Pt]N nanowires was studied by measuring the DW velocity under a magnetic field (H) and an electric current (J) in two extreme regimes of DW creep and flow. Two important findings are addressed. One is that the field-driven DW velocity increases with increasing N in the flow regime, whereas the trend is inverted in the creep regime. The other is that the sign of spin current-induced effective field is gradually reversed with increasing N in both DW creep and flow regimes. To reveal the underlying mechanism of new findings, we performed further experiment and micromagnetic simulation, from which we found that the observed phenomena can be explained by the combined effect of the DW anisotropy, Dzyaloshinskii-Moriya interaction, spin-Hall effect, and spin-transfer torques. Our results shed light on the mechanism of DW dynamics in novel amorphous PMA nanowires, so that this work may open a path to utilize the amorphous PMA in emerging DW-based spintronic devices.
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Affiliation(s)
- Y H Choi
- Department of Physics, Sogang University, Seoul 121-742 Korea
| | - Y Yoshimura
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K-J Kim
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Lee
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - T W Kim
- Department of Advanced Materials Engineering, Sejong University, Seoul 143-747 Korea
| | - T Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - C-Y You
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - M H Jung
- Department of Physics, Sogang University, Seoul 121-742 Korea
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Pulecio JF, Warnicke P, Pollard SD, Arena DA, Zhu Y. Coherence and modality of driven interlayer-coupled magnetic vortices. Nat Commun 2014; 5:3760. [DOI: 10.1038/ncomms4760] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 03/31/2014] [Indexed: 11/09/2022] Open
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Fukami S, Yamanouchi M, Ikeda S, Ohno H. Depinning probability of a magnetic domain wall in nanowires by spin-polarized currents. Nat Commun 2014; 4:2293. [PMID: 23945735 DOI: 10.1038/ncomms3293] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 07/11/2013] [Indexed: 11/09/2022] Open
Abstract
Current-induced magnetic domain wall motion is attractive for manipulating magnetization direction in spintronics devices, which open a new era of electronics. Up to now, in spite of a crucial significance to applications, investigation on a current-induced domain wall depinning probability, especially in sub-nano to a-few-nanosecond range has been lacking. Here we report on the probability of the depinning in perpendicularly magnetized Co/Ni nanowires in this timescale. A high depinning probability was obtained even for 2-ns pulses with a current density of less than 10¹² A m⁻². A one-dimensional Landau-Lifshitz-Gilbert calculation taking into account thermal fluctuations reproduces well the experimental results. We also calculate the depinning probability as functions of various parameters and found that parameters other than the coercive field do not affect the transition width of the probability. These findings will allow one to design high-speed and reliable magnetic devices based on the domain wall motion.
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Affiliation(s)
- S Fukami
- Center for Spintronics Integrated Systems, Tohoku University, Sendai 980-8577, Japan
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Biziere N, Gatel C, Lassalle-Balier R, Clochard MC, Wegrowe JE, Snoeck E. Imaging the fine structure of a magnetic domain wall in a Ni nanocylinder. Nano Lett 2013; 13:2053-7. [PMID: 23586647 PMCID: PMC3650658 DOI: 10.1021/nl400317j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We present the first experimental imaging of the internal DW structure in 55 and 85 nm diameter Ni nanocylinders, using electron holography combined with micromagnetic calculations. We demonstrate the magnetic transition from a hybrid magnetic state with both vortex and transverse DW in 85 nm diameter Ni nanocylinders to a pure transverse wall in thinner nanowires. This is particularly important as DWs in nanocylinders are model systems to go beyond the classical Walker limit.
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