1
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Qi L, Fan J, Cai H, Fang Z. A Survey of Emerging Memory in a Microcontroller Unit. Micromachines (Basel) 2024; 15:488. [PMID: 38675299 PMCID: PMC11051827 DOI: 10.3390/mi15040488] [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] [Received: 02/29/2024] [Revised: 03/26/2024] [Accepted: 03/28/2024] [Indexed: 04/28/2024]
Abstract
In the era of widespread edge computing, energy conservation modes like complete power shutdown are crucial for battery-powered devices, but they risk data loss in volatile memory. Energy autonomous systems, relying on ambient energy, face operational challenges due to power losses. Recent advancements in emerging nonvolatile memories (NVMs) like FRAM, RRAM, MRAM, and PCM offer mature solutions to sustain work progress with minimal energy overhead during outages. This paper thoroughly reviews utilizing emerging NVMs in microcontroller units (MCUs), comparing their key attributes to describe unique benefits and potential applications. Furthermore, we discuss the intricate details of NVM circuit design and NVM-driven compute-in-memory (CIM) architectures. In summary, integrating emerging NVMs into MCUs showcases promising prospects for next-generation applications such as Internet of Things and neural networks.
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Affiliation(s)
| | | | - Hao Cai
- School of Integrated Circuits, Southeast University, Nanjing 210096, China; (L.Q.); (J.F.); (Z.F.)
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2
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Lack W, Jenkins S, Meo A, Chantrell RW, McKenna KM, Evans RFL. Thermodynamic properties and switching dynamics of perpendicular shape anisotropy MRAM. J Phys Condens Matter 2024; 36:145801. [PMID: 38157556 DOI: 10.1088/1361-648x/ad19a0] [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] [Received: 06/28/2023] [Accepted: 12/28/2023] [Indexed: 01/03/2024]
Abstract
The power consumption of modern random access memory (RAM) has been a motivation for the development of low-power non-volatile magnetic RAM (MRAM). Based on a CoFeB/MgO magnetic tunnel junction, MRAM must satisfy high thermal stability and a low writing current while being scaled down to a sub-20 nm size to compete with the densities of current RAM technology. A recent development has been to exploit perpendicular shape anisotropy along the easy axis by creating tower structures, with the free layers' thickness (along the easy axis) being larger than its width. Here we use an atomistic model to explore the temperature dependent properties of thin cylindrical MRAM towers of 5 nm diameter while scaling down the free layer from 48 to 8 nm thick. We find thermal fluctuations are a significant driving force for the switching mechanism at operational temperatures by analysing the switching field distribution from hysteresis data. We find that a reduction of the free layer thickness below 18 nm rapidly loses shape anisotropy, and consequently stability, even at 0 K. Additionally, there is a change in the switching mechanism as the free layer is reduced to 8 nm. Coherent rotation is observed for the 8 nm free layer, while all taller towers demonstrate incoherent rotation via a propagated domain wall.
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Affiliation(s)
- Wayne Lack
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Sarah Jenkins
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Andrea Meo
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Roy W Chantrell
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Keith M McKenna
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
| | - Richard F L Evans
- School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom
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3
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Shao Y, Duffee C, Raimondo E, Davila N, Lopez-Dominguez V, Katine JA, Finocchio G, Khalili Amiri P. Probabilistic computing with voltage-controlled dynamics in magnetic tunnel junctions. Nanotechnology 2023; 34. [PMID: 37669644 DOI: 10.1088/1361-6528/acf6c7] [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] [Received: 06/08/2023] [Accepted: 09/05/2023] [Indexed: 09/07/2023]
Abstract
Probabilistic (p-) computing is a physics-based approach to addressing computational problems which are difficult to solve by conventional von Neumann computers. A key requirement for p-computing is the realization of fast, compact, and energy-efficient probabilistic bits. Stochastic magnetic tunnel junctions (MTJs) with low energy barriers, where the relative dwell time in each state is controlled by current, have been proposed as a candidate to implement p-bits. This approach presents challenges due to the need for precise control of a small energy barrier across large numbers of MTJs, and due to the need for an analog control signal. Here we demonstrate an alternative p-bit design based on perpendicular MTJs that uses the voltage-controlled magnetic anisotropy (VCMA) effect to create the random state of a p-bit on demand. The MTJs are stable (i.e. have large energy barriers) in the absence of voltage, and VCMA-induced dynamics are used to generate random numbers in less than 10 ns/bit. We then show a compact method of implementing p-bits by using VC-MTJs without a bias current. As a demonstration of the feasibility of the proposed p-bits and high quality of the generated random numbers, we solve up to 40 bit integer factorization problems using experimental bit-streams generated by VC-MTJs. Our proposal can impact the development of p-computers, both by supporting a fully spintronic implementation of a p-bit, and alternatively, by enabling true random number generation at low cost for ultralow-power and compact p-computers implemented in complementary metal-oxide semiconductor chips.
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Affiliation(s)
- Yixin Shao
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, United States of America
| | - Christian Duffee
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, United States of America
| | - Eleonora Raimondo
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina I-98166, Italy
| | - Noraica Davila
- Western Digital Corporation, San Jose, CA 95119, United States of America
| | - Victor Lopez-Dominguez
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, United States of America
- Institute of Advanced Materials (INAM), Universitat Jaume I, Castellón, E-12006, Spain
| | - Jordan A Katine
- Western Digital Corporation, San Jose, CA 95119, United States of America
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina I-98166, Italy
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL 60208, United States of America
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4
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Kateel V, Krizakova V, Rao S, Cai K, Gupta M, Monteiro MG, Yasin F, Sorée B, De Boeck J, Couet S, Gambardella P, Kar GS, Garello K. Field-Free Spin-Orbit Torque Driven Switching of Perpendicular Magnetic Tunnel Junction through Bending Current. Nano Lett 2023. [PMID: 37295781 DOI: 10.1021/acs.nanolett.3c00639] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Current-induced spin-orbit torques (SOTs) enable fast and efficient manipulation of the magnetic state of magnetic tunnel junctions (MTJs), making them attractive for memory, in-memory computing, and logic applications. However, the requirement of the external magnetic field to achieve deterministic switching in perpendicularly magnetized SOT-MTJs limits its implementation for practical applications. Here, we introduce a field-free switching (FFS) solution for the SOT-MTJ device by shaping the SOT channel to create a "bend" in the SOT current. The resulting bend in the charge current creates a spatially nonuniform spin current, which translates into inhomogeneous SOT on an adjacent magnetic free layer enabling deterministic switching. We demonstrate FFS experimentally on scaled SOT-MTJs at nanosecond time scales. This proposed scheme is scalable, material-agnostic, and readily compatible with wafer-scale manufacturing, thus creating a pathway for developing purely current-driven SOT systems.
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Affiliation(s)
- Vaishnavi Kateel
- IMEC Kapeldreef 75, B-3001 Leuven, Belgium
- Department of Electrical Engineering ESAT, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Viola Krizakova
- Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
| | | | | | | | - Maxwel Gama Monteiro
- IMEC Kapeldreef 75, B-3001 Leuven, Belgium
- Department of Electrical Engineering ESAT, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | | | - Bart Sorée
- IMEC Kapeldreef 75, B-3001 Leuven, Belgium
- Department of Electrical Engineering ESAT, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | - Johan De Boeck
- IMEC Kapeldreef 75, B-3001 Leuven, Belgium
- Department of Electrical Engineering ESAT, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
| | | | | | | | - Kevin Garello
- IMEC Kapeldreef 75, B-3001 Leuven, Belgium
- Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France
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5
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Fiorentini S, Jørstad NP, Ender J, de Orio RL, Selberherr S, Bendra M, Goes W, Sverdlov V. Finite Element Approach for the Simulation of Modern MRAM Devices. Micromachines (Basel) 2023; 14:mi14050898. [PMID: 37241522 DOI: 10.3390/mi14050898] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 04/14/2023] [Accepted: 04/20/2023] [Indexed: 05/28/2023]
Abstract
Because of their nonvolatile nature and simple structure, the interest in MRAM devices has been steadily growing in recent years. Reliable simulation tools, capable of handling complex geometries composed of multiple materials, provide valuable help in improving the design of MRAM cells. In this work, we describe a solver based on the finite element implementation of the Landau-Lifshitz-Gilbert equation coupled to the spin and charge drift-diffusion formalism. The torque acting in all layers from different contributions is computed from a unified expression. In consequence of the versatility of the finite element implementation, the solver is applied to switching simulations of recently proposed structures based on spin-transfer torque, with a double reference layer or an elongated and composite free layer, and of a structure combining spin-transfer and spin-orbit torques.
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Affiliation(s)
- Simone Fiorentini
- Christian Doppler Laboratory for Nonvolatile Magnetoresistive Memory and Logic at the Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
| | - Nils Petter Jørstad
- Christian Doppler Laboratory for Nonvolatile Magnetoresistive Memory and Logic at the Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
| | - Johannes Ender
- Christian Doppler Laboratory for Nonvolatile Magnetoresistive Memory and Logic at the Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
| | | | - Siegfried Selberherr
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
| | - Mario Bendra
- Christian Doppler Laboratory for Nonvolatile Magnetoresistive Memory and Logic at the Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
| | | | - Viktor Sverdlov
- Christian Doppler Laboratory for Nonvolatile Magnetoresistive Memory and Logic at the Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
- Institute for Microelectronics, TU Wien, Gußhausstraße 27-29/E360, 1040 Vienna, Austria
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6
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Li K, Feng J, Yuan X, Gan L, Lu Z, Xiong R. Study on a new manner of the magnetization switching actuated by a unidirectional pulse current. Nanotechnology 2021; 33:025001. [PMID: 34614479 DOI: 10.1088/1361-6528/ac2d48] [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] [Received: 06/18/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
A new writing scheme with a unidirectional pulse current is proposed for spin transfer torque (STT) based magnetic random-access memory (MRAM). To investigate the feasibility of the writing scheme, bilayered nano-pillars composed of a soft layer with small in-plane shape anisotropy and a hard layer with either large perpendicular anisotropy (PMA) or in-plane anisotropy (IMA) are designed and their switching behaviors are studied. It is found that in either type of bilayered nano-pillars, with the aid of the attached hard layer, the magnetization of the soft layer can be switched back and forth under a unidirectional pulse current. In an IMA/IMA nano-pillar, the magnetization of the free layer (FL) can achieve excellent alignment, which is in contrast to the IMA/PMA nano-pillar. By optimizing the dimensions and magnetic parameters of the IMA/IMA nano-pillar, a decently low switching current density (4.3 × 1011A m-2) and ultrashort switching time (<1 ns) can be reached. Based on these results, the unidirectional writing scheme is practical if an IMA/IMA bilayer is used to replace the FL in a magnetic tunnel junction. Considering that a unidirectional writing scheme can enable the application of materials with high spin polarization such as half metals, and avoid the injection of writing current into junction using a special design, it may be very promising for STT-MRAM.
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Affiliation(s)
- K Li
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - J Feng
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - X Yuan
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - L Gan
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - Z Lu
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - R Xiong
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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Bian Z, Hong X, Guo Y, Naviner L, Ge W, Cai H. Investigation of PVT-Aware STT- MRAM Sensing Circuits for Low-VDD Scenario. Micromachines (Basel) 2021; 12:mi12050551. [PMID: 34066185 PMCID: PMC8151166 DOI: 10.3390/mi12050551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 12/02/2022]
Abstract
Spintronic based embedded magnetic random access memory (eMRAM) is becoming a foundry validated solution for the next-generation nonvolatile memory applications. The hybrid complementary metal-oxide-semiconductor (CMOS)/magnetic tunnel junction (MTJ) integration has been selected as a proper candidate for energy harvesting, area-constraint and energy-efficiency Internet of Things (IoT) systems-on-chips. Multi-VDD (low supply voltage) techniques were adopted to minimize energy dissipation in MRAM, at the cost of reduced writing/sensing speed and margin. Meanwhile, yield can be severely affected due to variations in process parameters. In this work, we conduct a thorough analysis of MRAM sensing margin and yield. We propose a current-mode sensing amplifier (CSA) named 1D high-sensing 1D margin, high 1D speed and 1D stability (HMSS-SA) with reconfigured reference path and pre-charge transistor. Process-voltage-temperature (PVT) aware analysis is performed based on an MTJ compact model and an industrial 28 nm CMOS technology, explicitly considering low-voltage (0.7 V), low tunneling magnetoresistance (TMR) (50%) and high temperature (85 °C) scenario as the worst sensing case. A case study takes a brief look at sensing circuits, which is applied to in-memory bit-wise computing. Simulation results indicate that the proposed high-sensing margin, high speed and stability sensing-sensing amplifier (HMSS-SA) achieves remarkable performance up to 2.5 GHz sensing frequency. At 0.65 V supply voltage, it can achieve 1 GHz operation frequency with only 0.3% failure rate.
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Affiliation(s)
- Zhongjian Bian
- National ASIC System Engineering Center, Southeast University, Nanjing 210096, China; (Z.B.); (X.H.); (Y.G.); (W.G.)
| | - Xiaofeng Hong
- National ASIC System Engineering Center, Southeast University, Nanjing 210096, China; (Z.B.); (X.H.); (Y.G.); (W.G.)
| | - Yanan Guo
- National ASIC System Engineering Center, Southeast University, Nanjing 210096, China; (Z.B.); (X.H.); (Y.G.); (W.G.)
| | - Lirida Naviner
- Laboratoire Traitement et Communication de L’Information, Télécom Paris, 91120 Palaiseau, France;
| | - Wei Ge
- National ASIC System Engineering Center, Southeast University, Nanjing 210096, China; (Z.B.); (X.H.); (Y.G.); (W.G.)
| | - Hao Cai
- National ASIC System Engineering Center, Southeast University, Nanjing 210096, China; (Z.B.); (X.H.); (Y.G.); (W.G.)
- Laboratoire Traitement et Communication de L’Information, Télécom Paris, 91120 Palaiseau, France;
- Correspondence: ; Tel.: +86-025-8379-5811
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Ryu J, Lee S, Lee KJ, Park BG. Current-Induced Spin-Orbit Torques for Spintronic Applications. Adv Mater 2020; 32:e1907148. [PMID: 32141681 DOI: 10.1002/adma.201907148] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Control of magnetization in magnetic nanostructures is essential for development of spintronic devices because it governs fundamental device characteristics such as energy consumption, areal density, and operation speed. In this respect, spin-orbit torque (SOT), which originates from the spin-orbit interaction, has been widely investigated due to its efficient manipulation of the magnetization using in-plane current. SOT spearheads novel spintronic applications including high-speed magnetic memories, reconfigurable logics, and neuromorphic computing. Herein, recent advances in SOT research, highlighting the considerable benefits and challenges of SOT-based spintronic devices, are reviewed. First, the materials and structural engineering that enhances SOT efficiency are discussed. Then major experimental results for field-free SOT switching of perpendicular magnetization are summarized, which includes the introduction of an internal effective magnetic field and the generation of a distinct spin current with out-of-plane spin polarization. Finally, advanced SOT functionalities are presented, focusing on the demonstration of reconfigurable and complementary operation in spin logic devices.
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Affiliation(s)
- Jeongchun Ryu
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Soogil Lee
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering and KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Anam-dong, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Byong-Guk Park
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
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Kim DW, Yi WS, Choi JY, Ashiba K, Baek JU, Jun HS, Kim JJ, Park JG. Double MgO-Based Perpendicular Magnetic Tunnel Junction for Artificial Neuron. Front Neurosci 2020; 14:309. [PMID: 32425744 PMCID: PMC7204637 DOI: 10.3389/fnins.2020.00309] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/16/2020] [Indexed: 11/13/2022] Open
Abstract
A perpendicular spin transfer torque (p-STT)-based neuron was developed for a spiking neural network (SNN). It demonstrated the integration behavior of a typical neuron in an SNN; in particular, the integration behavior corresponding to magnetic resistance change gradually increased with the input spike number. This behavior occurred when the spin electron directions between double Co2Fe6B2 free and pinned layers in the p-STT-based neuron were switched from parallel to antiparallel states. In addition, a neuron circuit for integrate-and-fire operation was proposed. Finally, pattern-recognition simulation was performed for a single-layer SNN.
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Affiliation(s)
- Dong Won Kim
- Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul, South Korea
| | - Woo Seok Yi
- Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang, South Korea
| | - Jin Young Choi
- MRAM Center, Department of Electronics and Computer Engineering, Hanyang University, Seoul, South Korea
| | - Kei Ashiba
- Wafer Engineering Department, SUMCO Corporation, Imari, Japan
| | - Jong Ung Baek
- Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul, South Korea
| | - Han Sol Jun
- Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul, South Korea
| | - Jae Joon Kim
- Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang, South Korea
| | - Jea Gun Park
- Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul, South Korea.,Wafer Engineering Department, SUMCO Corporation, Imari, Japan
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10
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Wang X, Krylyuk S, Josell D, Zhang D, Wang JP, Gopman DB. Effect of oblique versus normal deposition orientation on the properties of perpendicularly magnetized L1 0 FePd thin films. IEEE Trans Magn 2020; 11:10.1109/LMAG.2020.3012081. [PMID: 33654328 PMCID: PMC7918265 DOI: 10.1109/lmag.2020.3012081] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Materials such as L10 Fe-based alloys with perpendicular magnetic anisotropy derived from crystal structure have the potential to deliver higher thermal stability of magnetic memory elements compared to materials whose anisotropy is derived from surfaces and interfaces. A number of processing parameters enable control of the quality and texture of L10 FePd among them, including substrate, deposition temperature, pressure and seed and buffer layer. The angle of inclination between the substrate and the sputtering target can also impact the texture of L10 crystallization of sputtered Fe-Pd and magnetic properties of the derived thin films. This study examines the difference between FePd layers that have been magnetron sputter deposited on Cr(15 nm)/Pt, Ir, or Ru(4 nm)/FePd (8 nm)/Ru(2 nm)/Ta(3 nm) substrate layers at an oblique angle (30° tilt from the sputtering target) versus normal incidence (target facing the substrate). X-ray diffraction, ferromagnetic resonance spectroscopy and vibrating sample magnetometry were used to compare the degree of L10 order and static and dynamic properties of films deposited under both conditions. The films grown using the oblique orientation exhibit a stronger degree of L10 orientation, a larger magnetic anisotropy energy and a lower Gilbert damping, on all three buffer layers.
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Affiliation(s)
- Xinjun Wang
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Sergiy Krylyuk
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Daniel Josell
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Delin Zhang
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Jian-Ping Wang
- Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455 USA
| | - Daniel B. Gopman
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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11
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Gopman DB, Chen P, Lau JW, Chavez AC, Carman GP, Finkel P, Staruch M, Shull RD. Large Interfacial Magnetostriction in (Co/Ni) 4/Pb(Mg 1/3Nb 2/3)O 3-PbTiO 3 Multiferroic Heterostructures. ACS Appl Mater Interfaces 2018; 10:24725-24732. [PMID: 29972304 DOI: 10.1021/acsami.8b06249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The magnetoelastic behavior of multiferroic heterostructures-coupling of magnetic anisotropy or domain dynamics to structural deformations-has been intensively studied for developing materials for energy-efficient, spin-based applications. Here, we report on a large, interface-dominated magnetostriction in (Co/Ni)4/Pb(Mg1/3Nb2/3)O3-PbTiO3 multiferroic heterostructures. Ferromagnetic resonance spectroscopy under voltage-induced strains enabled estimation of the saturation magnetostriction as a function of Ni thickness. The volume and the interface components to the saturation magnetostriction are (6.6 ± 0.9) × 10-6 and (-2.2 ± 0.2) × 10-14 m, respectively. Similar to perpendicular magnetic anisotropy in Co/Ni, the large, negative magnetostriction originates from the Co/Ni interfaces. This interfacial functionality delivers an effect over 300% larger than the bulk contribution and can enable low-energy, nanoelectronic devices that combine the tunable magnetic and magnetostrictive properties of Co/Ni multilayers with the ferroelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3.
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Affiliation(s)
- Daniel B Gopman
- Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Peijie Chen
- Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - June W Lau
- Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
| | - Andres C Chavez
- Mechanical and Aerospace Engineering Department , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Gregory P Carman
- Mechanical and Aerospace Engineering Department , University of California, Los Angeles , Los Angeles , California 90095 , United States
| | - Peter Finkel
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Margo Staruch
- Materials Science & Technology Division , Naval Research Laboratory , Washington , District of Columbia 20375 , United States
| | - Robert D Shull
- Materials Science and Engineering Division , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
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Zhang J, Garg C, Phung T, Rettner C, Hughes BP, Yang SH, Jiang Y, Parkin SSP. Role of Micromagnetic States on Spin-Orbit Torque-Switching Schemes. Nano Lett 2018; 18:4074-4080. [PMID: 29905078 DOI: 10.1021/acs.nanolett.7b05247] [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: 06/08/2023]
Abstract
Three-terminal spintronic memory devices based on the controlled manipulation of the proximate magnetization of a magnetic nanoelement using spin-orbit torques (SOTs) have attracted growing interest recently. These devices are nonvolatile, can operate at high speeds with low error rates, and have essentially infinite endurance, making them promising candidates for high-speed cache memory. Typically, the magnetization and spin polarization in these devices are collinear to one another, leading to a finite incubation time associated with the switching process. While switching can also be achieved when the magnetization easy axis and spin polarization are noncollinear, this requires the application of an external magnetic field for deterministic switching. Here, we demonstrate a novel SOT scheme that exploits non-uniform micromagnetic states to achieve deterministic switching when the spin polarization and magnetic moment axis are noncollinear to one another in the absence of external magnetic field. We also explore the use of a highly efficient SOT generator, oxygen-doped tungsten in the three-terminal device geometry, confirming its -50% spin Hall angle. Lastly, we illustrate how this scheme may potentially be useful for nanomagnetic logic applications.
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Affiliation(s)
- Jie Zhang
- School of Materials Science and Engineering , University of Science & Technology Beijing , Beijing 100083 , China
- IBM Almaden Research Center , San Jose , California 95120 , United States
| | - Chirag Garg
- IBM Almaden Research Center , San Jose , California 95120 , United States
- Max Planck Institute for Microstructure Physics , Halle (Saale) D06120 , Germany
| | - Timothy Phung
- IBM Almaden Research Center , San Jose , California 95120 , United States
| | - Charles Rettner
- IBM Almaden Research Center , San Jose , California 95120 , United States
| | - Brian P Hughes
- IBM Almaden Research Center , San Jose , California 95120 , United States
| | - See-Hun Yang
- IBM Almaden Research Center , San Jose , California 95120 , United States
| | - Yong Jiang
- School of Materials Science and Engineering , University of Science & Technology Beijing , Beijing 100083 , China
| | - Stuart S P Parkin
- IBM Almaden Research Center , San Jose , California 95120 , United States
- Max Planck Institute for Microstructure Physics , Halle (Saale) D06120 , Germany
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Aradhya SV, Rowlands GE, Oh J, Ralph DC, Buhrman RA. Nanosecond-Timescale Low Energy Switching of In-Plane Magnetic Tunnel Junctions through Dynamic Oersted-Field-Assisted Spin Hall Effect. Nano Lett 2016; 16:5987-5992. [PMID: 27327619 DOI: 10.1021/acs.nanolett.6b01443] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We investigate fast-pulse switching of in-plane-magnetized magnetic tunnel junctions (MTJs) within 3-terminal devices in which spin-transfer torque is applied to the MTJ by the giant spin Hall effect. We measure reliable switching, with write error rates down to 10-5, using current pulses as short as just 2 ns in duration. This represents the fastest reliable switching reported to date for any spin-torque-driven magnetic memory geometry and corresponds to a characteristic time scale that is significantly shorter than predicted possible within a macrospin model for in-plane MTJs subject to thermal fluctuations at room temperature. Using micromagnetic simulations, we show that in the three-terminal spin-Hall devices the Oersted magnetic field generated by the pulse current strongly modifies the magnetic dynamics excited by the spin-Hall torque, enabling this unanticipated performance improvement. Our results suggest that in-plane MTJs controlled by Oersted-field-assisted spin-Hall torque are a promising candidate for both cache memory applications requiring high speed and for cryogenic memories requiring low write energies.
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Affiliation(s)
- S V Aradhya
- Cornell University , Ithaca, New York 14853, United States
| | - G E Rowlands
- Cornell University , Ithaca, New York 14853, United States
| | - J Oh
- Cornell University , Ithaca, New York 14853, United States
| | - D C Ralph
- Cornell University , Ithaca, New York 14853, United States
- Kavli Institute at Cornell , Ithaca, New York 14853, United States
| | - R A Buhrman
- Cornell University , Ithaca, New York 14853, United States
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Pushp A, Phung T, Rettner C, Hughes BP, Yang SH, Parkin SS. Giant thermal spin-torque-assisted magnetic tunnel junction switching. Proc Natl Acad Sci U S A 2015; 112:6585-90. [PMID: 25971730 DOI: 10.1073/pnas.1507084112] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spin-polarized charge currents induce magnetic tunnel junction (MTJ) switching by virtue of spin-transfer torque (STT). Recently, by taking advantage of the spin-dependent thermoelectric properties of magnetic materials, novel means of generating spin currents from temperature gradients, and their associated thermal-spin torques (TSTs), have been proposed, but so far these TSTs have not been large enough to influence MTJ switching. Here we demonstrate significant TSTs in MTJs by generating large temperature gradients across ultrathin MgO tunnel barriers that considerably affect the switching fields of the MTJ. We attribute the origin of the TST to an asymmetry of the tunneling conductance across the zero-bias voltage of the MTJ. Remarkably, we estimate through magneto-Seebeck voltage measurements that the charge currents that would be generated due to the temperature gradient would give rise to STT that is a thousand times too small to account for the changes in switching fields that we observe.
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Lin AL, Peng H, Liu Z, Wu T, Su C, Loh KP, Chen W, Wee ATS. Room temperature magnetic graphene oxide-iron oxide nanocomposite based magnetoresistive random access memory devices via spin-dependent trapping of electrons. Small 2014; 10:1945-1952. [PMID: 24578292 DOI: 10.1002/smll.201302986] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 01/08/2014] [Indexed: 06/03/2023]
Affiliation(s)
- Aigu L Lin
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, 28 Medical Drive, Singapore, 117456; Department of Physics, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore, 117542
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