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Xu H, Liu Y, Finocchio G, Wang KL, Yu G. Progress and perspective on the topological spin textures in two-dimensional van der Waals magnets. Sci Bull (Beijing) 2024:S2095-9273(24)00223-8. [PMID: 38653683 DOI: 10.1016/j.scib.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Affiliation(s)
- Hongjun Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Yizhou Liu
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina 98166, Italy
| | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles CA 90095, USA
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.
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2
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Shi J, Arpaci S, Lopez-Dominguez V, Sangwan VK, Mahfouzi F, Kim J, Athas JG, Hamdi M, Aygen C, Arava H, Phatak C, Carpentieri M, Jiang JS, Grayson MA, Kioussis N, Finocchio G, Hersam MC, Khalili Amiri P. Electrically Controlled All-Antiferromagnetic Tunnel Junctions on Silicon with Large Room-Temperature Magnetoresistance. Adv Mater 2024:e2312008. [PMID: 38501999 DOI: 10.1002/adma.202312008] [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: 11/12/2023] [Revised: 02/11/2024] [Indexed: 03/20/2024]
Abstract
Antiferromagnetic (AFM) materials are a pathway to spintronic memory and computing devices with unprecedented speed, energy efficiency, and bit density. Realizing this potential requires AFM devices with simultaneous electrical writing and reading of information, which are also compatible with established silicon-based manufacturing. Recent experiments have shown tunneling magnetoresistance (TMR) readout in epitaxial AFM tunnel junctions. However, these TMR structures are not grown using a silicon-compatible deposition process, and controlling their AFM order required external magnetic fields. Here it is shown three-terminal AFM tunnel junctions based on the noncollinear antiferromagnet PtMn3 , sputter-deposited on silicon. The devices simultaneously exhibit electrical switching using electric currents, and electrical readout by a large room-temperature TMR effect. First-principles calculations explain the TMR in terms of the momentum-resolved spin-dependent tunneling conduction in tunnel junctions with noncollinear AFM electrodes.
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Affiliation(s)
- Jiacheng Shi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sevdenur Arpaci
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Victor Lopez-Dominguez
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Institute of Advanced Materials (INAM), Universitat Jaume I, Castellón, 12006, Spain
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Farzad Mahfouzi
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jinwoong Kim
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Jordan G Athas
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mohammad Hamdi
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Can Aygen
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Hanu Arava
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Charudatta Phatak
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, Bari, 70125, Italy
| | - Jidong S Jiang
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Matthew A Grayson
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
| | - Nicholas Kioussis
- Department of Physics and Astronomy, California State University Northridge, Northridge, CA, 91330, USA
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, 98166, Italy
| | - Mark C Hersam
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
- Applied Physics Program, Northwestern University, Evanston, IL, 60208, USA
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3
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Darwin E, Tomasello R, Shepley PM, Satchell N, Carpentieri M, Finocchio G, Hickey BJ. Antiferromagnetic interlayer exchange coupled Co 68B 32/Ir/Pt multilayers. Sci Rep 2024; 14:95. [PMID: 38168577 PMCID: PMC10761723 DOI: 10.1038/s41598-023-49976-4] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 12/14/2023] [Indexed: 01/05/2024] Open
Abstract
Synthetic antiferromagnetic structures can exhibit the advantages of high velocity similarly to antiferromagnets with the additional benefit of being imaged and read-out through techniques applied to ferromagnets. Here, we explore the potential and limits of synthetic antiferromagnets to uncover ways to harness their valuable properties for applications. Two synthetic antiferromagnetic systems have been engineered and systematically investigated to provide an informed basis for creating devices with maximum potential for data storage, logic devices, and skyrmion racetrack memories. The two systems considered are (system 1) CoB/Ir/Pt of N repetitions with Ir inducing the negative coupling between the ferromagnetic layers and (system 2) two ferromagnetically coupled multilayers of CoB/Ir/Pt, coupled together antiferromagnetically with an Ir layer. From the hysteresis, it is found that system 1 shows stable antiferromagnetic interlayer exchange coupling between each magnetic layer up to N = 7. Using Kerr imaging, the two ferromagnetic multilayers in system 2 are shown to undergo separate maze-like switches during hysteresis. Both systems are also studied as a function of temperature and show different behaviors. Micromagnetic simulations predict that in both systems the skyrmion Hall angle is suppressed with the skyrmion velocity five times higher in system 1 than system 2.
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Affiliation(s)
- Emily Darwin
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
- Department of Electrical and Information Engineering, Politecnico Di Bari, Via E. Orabona 4, 70125, Bari, Italy
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico Di Bari, Via E. Orabona 4, 70125, Bari, Italy
| | - Philippa M Shepley
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Nathan Satchell
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
- Department of Physics, Texas State University, San Marcos, TX, 78666, USA
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico Di Bari, Via E. Orabona 4, 70125, Bari, Italy
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, 98166, Messina, Italy.
| | - B J Hickey
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
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4
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Siracusano G, La Corte A, Nucera AG, Gaeta M, Chiappini M, Finocchio G. Effective processing pipeline PACE 2.0 for enhancing chest x-ray contrast and diagnostic interpretability. Sci Rep 2023; 13:22471. [PMID: 38110512 PMCID: PMC10728198 DOI: 10.1038/s41598-023-49534-y] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 12/09/2023] [Indexed: 12/20/2023] Open
Abstract
Preprocessing is an essential task for the correct analysis of digital medical images. In particular, X-ray imaging might contain artifacts, low contrast, diffractions or intensity inhomogeneities. Recently, we have developed a procedure named PACE that is able to improve chest X-ray (CXR) images including the enforcement of clinical evaluation of pneumonia originated by COVID-19. At the clinical benchmark state of this tool, there have been found some peculiar conditions causing a reduction of details over large bright regions (as in ground-glass opacities and in pleural effusions in bedridden patients) and resulting in oversaturated areas. Here, we have significantly improved the overall performance of the original approach including the results in those specific cases by developing PACE2.0. It combines 2D image decomposition, non-local means denoising, gamma correction, and recursive algorithms to improve image quality. The tool has been evaluated using three metrics: contrast improvement index, information entropy, and effective measure of enhancement, resulting in an average increase of 35% in CII, 7.5% in ENT, 95.6% in EME and 13% in BRISQUE against original radiographies. Additionally, the enhanced images were fed to a pre-trained DenseNet-121 model for transfer learning, resulting in an increase in classification accuracy from 80 to 94% and recall from 89 to 97%, respectively. These improvements led to a potential enhancement of the interpretability of lesion detection in CXRs. PACE2.0 has the potential to become a valuable tool for clinical decision support and could help healthcare professionals detect pneumonia more accurately.
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Affiliation(s)
- Giulio Siracusano
- Department of Electric, Electronic and Computer Engineering, University of Catania, Viale Andrea Doria 6, 95125, Catania, Italy.
| | - Aurelio La Corte
- Department of Electric, Electronic and Computer Engineering, University of Catania, Viale Andrea Doria 6, 95125, Catania, Italy
| | - Annamaria Giuseppina Nucera
- Unit of Radiology, Department of Advanced Diagnostic-Therapeutic Technologies, "Bianchi-Melacrino-Morelli" Hospital, Reggio Calabria, Via Giuseppe Melacrino, 21, 89124, Reggio Calabria, Italy
| | - Michele Gaeta
- Department of Biomedical Sciences, Dental and of Morphological and Functional Images, University of Messina, Via Consolare Valeria 1, 98125, Messina, Italy
| | - Massimo Chiappini
- Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143, Rome, Italy.
- Maris Scarl, Via Vigna Murata 606, 00143, Rome, Italy.
| | - Giovanni Finocchio
- Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata 605, 00143, Rome, Italy.
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, V.le F. Stagno D'Alcontres 31, 98166, Messina, Italy.
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5
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Hamadeh AA, Slobodianiuk D, Moukhader R, Melkov G, Borynskyi V, Mohseni M, Finocchio G, Lomakin V, Verba R, de Loubens G, Pirro P, Klein O. Simultaneous multitone microwave emission by dc-driven spintronic nano-element. Sci Adv 2023; 9:eadk1430. [PMID: 38091395 PMCID: PMC10848702 DOI: 10.1126/sciadv.adk1430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 11/14/2023] [Indexed: 02/12/2024]
Abstract
Current-induced self-sustained magnetization oscillations in spin-torque nano-oscillators (STNOs) are promising candidates for ultra-agile microwave sources or detectors. While usually STNOs behave as a monochromatic source, we report here clear bimodal simultaneous emission of incommensurate microwave oscillations in the frequency range of 6 to 10 gigahertz at femtowatt level power. These two tones correspond to two parametrically coupled eigenmodes with tunable splitting. The emission range is crucially sensitive to the change in hybridization of the eigenmodes of free and fixed layers, for instance, through a slight tilt of the applied magnetic field from the normal of the nanopillar. Our experimental findings are supported both analytically and by micromagnetic simulations, which ascribe the process to four-magnon scattering between a pair of radially symmetric magnon modes and a pair of magnon modes with opposite azimuthal index. Our findings pave the way for enhanced cognitive telecommunications and neuromorphic systems that use frequency multiplexing to improve communication performance.
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Affiliation(s)
- Alexandre Abbass Hamadeh
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Denys Slobodianiuk
- Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
- Institute of Magnetism, Kyiv 03142, Ukraine
| | - Rayan Moukhader
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, 98166 Messina, Italy
| | - Gennadiy Melkov
- Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
| | | | - Morteza Mohseni
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, 98166 Messina, Italy
| | - Vitaly Lomakin
- Center for Magnetic Recording Research, University of California San Diego, La Jolla, CA 92093-0401, USA
| | | | | | - Philipp Pirro
- Fachbereich Physik and Landesforschungszentrum OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, 67663 Kaiserslautern, Germany
| | - Olivier Klein
- Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, Spintec, 38054 Grenoble, France
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6
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He B, Tomasello R, Luo X, Zhang R, Nie Z, Carpentieri M, Han X, Finocchio G, Yu G. All-Electrical 9-Bit Skyrmion-Based Racetrack Memory Designed with Laser Irradiation. Nano Lett 2023; 23:9482-9490. [PMID: 37818857 DOI: 10.1021/acs.nanolett.3c02978] [Citation(s) in RCA: 2] [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] [Indexed: 10/13/2023]
Abstract
Racetrack memories with magnetic skyrmions have recently been proposed as a promising storage technology. To be appealing, several challenges must still be faced for the deterministic generation of skyrmions, their high-fidelity transfer, and accurate reading. Here, we realize the first proof-of-concept of a 9-bit skyrmion racetrack memory with all-electrical controllable functionalities implemented in the same device. The key ingredient is the generation of a tailored nonuniform distribution of magnetic anisotropy via laser irradiation in order to (i) create a well-defined skyrmion nucleation center, (ii) define the memory cells hosting the information coded as the presence/absence of skyrmions, and (iii) improve the signal-to-noise ratio of anomalous Hall resistance measurements. This work introduces a strategy to unify previous findings and predictions for the development of a generation of racetrack memories with robust control of skyrmion nucleation and position, as well as effective skyrmion electrical detection.
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Affiliation(s)
- Bin He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico of Bari, Bari 70125, Italy
| | - Xuming Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Ran Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Zhuyang Nie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico of Bari, Bari 70125, Italy
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina 98166, Italy
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
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7
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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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8
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Rodrigues D, Tomasello R, Siracusano G, Carpentieri M, Finocchio G. Ultra-sensitive voltage-controlled skyrmion-based spintronic diode. Nanotechnology 2023. [PMID: 37267927 DOI: 10.1088/1361-6528/acdad6] [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: 06/04/2023]
Abstract
We have designed a passive spintronic diode based on a single skyrmion stabilized in a magnetic tunnel junction and studied its dynamics induced by voltage-controlled anisotropy (VCMA) and Dzyaloshinskii-Moriya interaction (VDMI). We have demonstrated that the sensitivity (rectified voltage over input microwave power) with realistic physical parameters and geometry can be larger than 10 kV/W which is one order of magnitude better than diodes employing a uniform ferromagnetic state. Our numerical and analytical results on the VCMA and VDMI-driven resonant excitation of skyrmions beyond the linear regime reveal a frequency dependence on the amplitude and no efficient parametric resonance. Skyrmions with a smaller radius produced higher sensitivities, demonstrating the efficient scalability of skyrmion-based spintronic diodes. These results pave the way for designing passive ultra-sensitive and energy efficient skyrmion-based microwave detectors.
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Affiliation(s)
- Davi Rodrigues
- Department of Electrical and Information Engineering, Politecnico di Bari, Via E. Orabona 4, Bari, Bari, Puglia, 70126, ITALY
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico di Bari, Via Edoardo Orabona 4, Bari, 70126, ITALY
| | - Giulio Siracusano
- Dept. of Electric, Electronic and computer Engineering, University of Catania, Viale Andrea Doria 6, Catania, 95131, ITALY
| | - Mario Carpentieri
- Electrical and Information Engineering, Politecnico di Bari, via E. Orabona 4, Bari, 70126, ITALY
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, Messina, 98166, ITALY
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9
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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Yıldırım O, Tomasello R, Feng Y, Carlotti G, Tacchi S, Vaghefi PM, Giordano A, Dutta T, Finocchio G, Hug HJ, Mandru AO. Tuning the Coexistence Regime of Incomplete and Tubular Skyrmions in Ferromagnetic/Ferrimagnetic/Ferromagnetic Trilayers. ACS Appl Mater Interfaces 2022; 14:34002-34010. [PMID: 35830277 DOI: 10.1021/acsami.2c06608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The development of skyrmionic devices requires a suitable tuning of material parameters to stabilize skyrmions and control their density. It has been demonstrated recently that different skyrmion types can be simultaneously stabilized at room temperature in heterostructures involving ferromagnets, ferrimagnets, and heavy metals, offering a new platform of coding binary information in the type of skyrmion instead of the presence/absence of skyrmions. Here, we tune the energy landscape of the two skyrmion types in such heterostructures by engineering the geometrical and material parameters of the individual layers. We find that a fine adjustment of the ferromagnetic layer thickness, and thus its magnetic anisotropy, allows the trilayer system to support either one of the skyrmion types or the coexistence of both and with varying densities.
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Affiliation(s)
- Oğuz Yıldırım
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Riccardo Tomasello
- Department of Electrical and Information Engineering, Politecnico di Bari, 70125 Bari, Italy
| | - Yaoxuan Feng
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Giovanni Carlotti
- Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia, Italy
| | - Silvia Tacchi
- Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, 06123 Perugia, Italy
| | - Pegah Mirzadeh Vaghefi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Anna Giordano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - Tanmay Dutta
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - Hans J Hug
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
- Department of Physics, University of Basel, CH-4056 Basel, Switzerland
| | - Andrada-Oana Mandru
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf, Switzerland
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11
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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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 Appl Mater 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] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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Li W, Bykova I, Zhang S, Yu G, Tomasello R, Carpentieri M, Liu Y, Guang Y, Gräfe J, Weigand M, Burn DM, van der Laan G, Hesjedal T, Yan Z, Feng J, Wan C, Wei J, Wang X, Zhang X, Xu H, Guo C, Wei H, Finocchio G, Han X, Schütz G. Anatomy of Skyrmionic Textures in Magnetic Multilayers. Adv Mater 2019; 31:e1807683. [PMID: 30735264 DOI: 10.1002/adma.201807683] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/28/2019] [Indexed: 06/09/2023]
Abstract
Room temperature magnetic skyrmions in magnetic multilayers are considered as information carriers for future spintronic applications. Currently, a detailed understanding of the skyrmion stabilization mechanisms is still lacking in these systems. To gain more insight, it is first and foremost essential to determine the full real-space spin configuration. Here, two advanced X-ray techniques are applied, based on magnetic circular dichroism, to investigate the spin textures of skyrmions in [Ta/CoFeB/MgO]n multilayers. First, by using ptychography, a high-resolution diffraction imaging technique, the 2D out-of-plane spin profile of skyrmions with a spatial resolution of 10 nm is determined. Second, by performing circular dichroism in resonant elastic X-ray scattering, it is demonstrated that the chirality of the magnetic structure undergoes a depth-dependent evolution. This suggests that the skyrmion structure is a complex 3D structure rather than an identical planar texture throughout the layer stack. The analyses of the spin textures confirm the theoretical predictions that the dipole-dipole interactions together with the external magnetic field play an important role in stabilizing sub-100 nm diameter skyrmions and the hybrid structure of the skyrmion domain wall. This combined X-ray-based approach opens the door for in-depth studies of magnetic skyrmion systems, which allows for precise engineering of optimized skyrmion heterostructures.
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Affiliation(s)
- Wenjing Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Iuliia Bykova
- Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569, Stuttgart, Germany
| | - Shilei Zhang
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Guoqiang Yu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Riccardo Tomasello
- Institute of Applied and Computational Mathematics, FORTH, GR-70013, Heraklion-Crete, Greece
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Polytechnic University of Bari, Bari, 70125, Italy
| | - Yizhou Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Yao Guang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Joachim Gräfe
- Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569, Stuttgart, Germany
| | - Markus Weigand
- Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569, Stuttgart, Germany
| | - David M Burn
- Magnetic Spectroscopy Group, Diamond Light Source, Didcot, OX11 0DE, UK
| | | | - Thorsten Hesjedal
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, UK
| | - Zhengren Yan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jiafeng Feng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Caihua Wan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Jinwu Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Xiao Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Xiaomin Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Hongjun Xu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Chenyang Guo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Hongxiang Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, 98166, Italy
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Gisela Schütz
- Max Planck Institute for Intelligent Systems, Heisenbergstraße 3, 70569, Stuttgart, Germany
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14
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Karakas V, Gokce A, Habiboglu AT, Arpaci S, Ozbozduman K, Cinar I, Yanik C, Tomasello R, Tacchi S, Siracusano G, Carpentieri M, Finocchio G, Hauet T, Ozatay O. Observation of Magnetic Radial Vortex Nucleation in a Multilayer Stack with Tunable Anisotropy. Sci Rep 2018; 8:7180. [PMID: 29739995 PMCID: PMC5940785 DOI: 10.1038/s41598-018-25392-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [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: 08/30/2017] [Accepted: 04/22/2018] [Indexed: 11/09/2022] Open
Abstract
Recently discovered exotic magnetic configurations, namely magnetic solitons appearing in the presence of bulk or interfacial Dzyaloshinskii-Moriya Interaction (i-DMI), have excited scientists to explore their potential applications in emerging spintronic technologies such as race-track magnetic memory, spin logic, radio frequency nano-oscillators and sensors. Such studies are motivated by their foreseeable advantages over conventional micro-magnetic structures due to their small size, topological stability and easy spin-torque driven manipulation with much lower threshold current densities giving way to improved storage capacity, and faster operation with efficient use of energy. In this work, we show that in the presence of i-DMI in Pt/CoFeB/Ti multilayers by tuning the magnetic anisotropy (both in-plane and perpendicular-to-plane) via interface engineering and postproduction treatments, we can stabilize a variety of magnetic configurations such as Néel skyrmions, horseshoes and most importantly, the recently predicted isolated radial vortices at room temperature and under zero bias field. Especially, the radial vortex state with its absolute convergence to or divergence from a single point can potentially offer exciting new applications such as particle trapping/detrapping in addition to magnetoresistive memories with efficient switching, where the radial vortex state can act as a source of spin-polarized current with radial polarization.
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Affiliation(s)
- Vedat Karakas
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey.
| | - Aisha Gokce
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
| | | | - Sevdenur Arpaci
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
| | - Kaan Ozbozduman
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
| | - Ibrahim Cinar
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey.,Department of Physics, Karamanoglu Mehmetbey University, 70100, Karaman, Turkey
| | - Cenk Yanik
- Sabanci University Nanotechnology Research and Application Center Tuzla, 34956, Istanbul, Turkey
| | - Riccardo Tomasello
- Department of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, Terni, Italy
| | - Silvia Tacchi
- Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, Università di Perugia, Perugia, Italy
| | - Giulio Siracusano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, I-70125, Bari, Italy
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
| | - Thomas Hauet
- Institut Jean Lamour, UMR CNRS-Université de Lorraine, 54506, Vandoeuvrelès Nancy, France
| | - Ozhan Ozatay
- Physics Department, Bogazici University, Bebek, 34342, Istanbul, Turkey
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15
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Giordano A, Verba R, Zivieri R, Laudani A, Puliafito V, Gubbiotti G, Tomasello R, Siracusano G, Azzerboni B, Carpentieri M, Slavin A, Finocchio G. Spin-Hall nano-oscillator with oblique magnetization and Dzyaloshinskii-Moriya interaction as generator of skyrmions and nonreciprocal spin-waves. Sci Rep 2016; 6:36020. [PMID: 27786261 PMCID: PMC5081538 DOI: 10.1038/srep36020] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [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: 06/30/2016] [Accepted: 10/06/2016] [Indexed: 11/18/2022] Open
Abstract
Spin-Hall oscillators (SHO) are promising sources of spin-wave signals for magnonics applications, and can serve as building blocks for magnonic logic in ultralow power computation devices. Thin magnetic layers used as “free” layers in SHO are in contact with heavy metals having large spin-orbital interaction, and, therefore, could be subject to the spin-Hall effect (SHE) and the interfacial Dzyaloshinskii-Moriya interaction (i-DMI), which may lead to the nonreciprocity of the excited spin waves and other unusual effects. Here, we analytically and micromagnetically study magnetization dynamics excited in an SHO with oblique magnetization when the SHE and i-DMI act simultaneously. Our key results are: (i) excitation of nonreciprocal spin-waves propagating perpendicularly to the in-plane projection of the static magnetization; (ii) skyrmions generation by pure spin-current; (iii) excitation of a new spin-wave mode with a spiral spatial profile originating from a gyrotropic rotation of a dynamical skyrmion. These results demonstrate that SHOs can be used as generators of magnetic skyrmions and different types of propagating spin-waves for magnetic data storage and signal processing applications.
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Affiliation(s)
- A Giordano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
| | - R Verba
- Institute of Magnetism, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - R Zivieri
- Department of Physics and Earth Sciences and CNISM Unit of Ferrara, University of Ferrara, Ferrara, Italy
| | - A Laudani
- Department of Engineering, University of Roma Tre, Roma, Italy
| | - V Puliafito
- Department of Engineering, University of Messina, Messina, Italy
| | - G Gubbiotti
- Istituto Officina dei Materiali del CNR (CNR-IOM), Sede Secondaria di Perugia, c/o Dipartimento di Fisica e Geologia, University of Perugia, Perugia, Italy
| | - R Tomasello
- Department of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, Terni, Italy
| | - G Siracusano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
| | - B Azzerboni
- Department of Engineering, University of Messina, Messina, Italy
| | - M Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, I-70125 Bari, Italy
| | - A Slavin
- Department of Physics, Oakland University, Rochester, MI 48309, USA
| | - G Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina, Italy
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16
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Siracusano G, La Corte A, Milazzo C, Anastasi GP, Finocchio G, Gaeta M. On the R 2⁎ relaxometry in complex multi-peak multi-Echo chemical shift-based water-fat quantification: Applications to the neuromuscular diseases. Magn Reson Imaging 2016; 35:4-14. [PMID: 27569370 DOI: 10.1016/j.mri.2016.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 08/03/2016] [Accepted: 08/20/2016] [Indexed: 12/31/2022]
Abstract
PURPOSE Investigation of the feasibility of the R2⁎ mapping techniques by using latest theoretical models corrected for confounding factors and optimized for signal to noise ratio. THEORY AND METHODS The improvement of the performance of state of the art magnetic resonance imaging (MRI) relaxometry algorithms is challenging because of a non-negligible bias and still unresolved numerical instabilities. Here, R2⁎ mapping reconstructions, including complex fitting with multi-spectral fat-correction by using single-decay and double-decay formulation, are deeply studied in order to investigate and identify optimal configuration parameters and minimize the occurrence of numerical artifacts. The effects of echo number, echo spacing, and fat/water relaxation model type are evaluated through both simulated and in-vivo data. We also explore the stability and feasibility of the fat/water relaxation model by analyzing the impact of high percentage of fat infiltrations and local transverse relaxation differences among biological species. RESULTS The main limits of the MRI relaxometry are the presence of bias and the occurrence of artifacts, which significantly affect its accuracy. Chemical-shift complex R2⁎-correct single-decay reconstructions exhibit a large bias in presence of a significant difference in the relaxation rates of fat and water and with fat concentration larger than 30%. We find that for fat-dominated tissues or in patients affected by extensive iron deposition, MRI reconstructions accounting for multi-exponential relaxation time provide accurate R2⁎ measurements and are less prone to numerical artifacts. CONCLUSIONS Complex fitting and fat-correction with multi-exponential decay formulation outperforms the conventional single-decay approximation in various diagnostic scenarios. Although it still lacks of numerical stability, which requires model enhancement and support from spectroscopy, it offers promising perspectives for the development of relaxometry as a reliable tool to improve tissue characterization and monitoring of neuromuscular disorders.
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Affiliation(s)
- Giulio Siracusano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, V.le F. D'alcontres, 31, 98166, Messina, Italy; Department of Computer Engineering and Telecommunications, University of Catania, Viale Andrea Doria 6, 95125, Catania, Italy.
| | - Aurelio La Corte
- Department of Computer Engineering and Telecommunications, University of Catania, Viale Andrea Doria 6, 95125, Catania, Italy
| | - Carmelo Milazzo
- Department of Biomedical sciences, Dental and of Morphological and Functional images, University of Messina, Via Consolare Valeria 1, 98125, Messina, Italy
| | - Giuseppe Pio Anastasi
- Department of Biomedical sciences, Dental and of Morphological and Functional images, University of Messina, Via Consolare Valeria 1, 98125, Messina, Italy
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, V.le F. D'alcontres, 31, 98166, Messina, Italy; Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via Vigna Murata 605, 00143, Roma, Italy
| | - Michele Gaeta
- Department of Biomedical sciences, Dental and of Morphological and Functional images, University of Messina, Via Consolare Valeria 1, 98125, Messina, Italy
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17
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Siracusano G, Tomasello R, Giordano A, Puliafito V, Azzerboni B, Ozatay O, Carpentieri M, Finocchio G. Magnetic Radial Vortex Stabilization and Efficient Manipulation Driven by the Dzyaloshinskii-Moriya Interaction and Spin-Transfer Torque. Phys Rev Lett 2016; 117:087204. [PMID: 27588879 DOI: 10.1103/physrevlett.117.087204] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Indexed: 06/06/2023]
Abstract
Solitons are very promising for the design of the next generation of ultralow power devices for storage and computation. The key ingredient to achieving this goal is the fundamental understanding of their stabilization and manipulation. Here, we show how the interfacial Dzyaloshinskii-Moriya Interaction (IDMI) is able to lift the energy degeneracy of a magnetic vortex state by stabilizing a topological soliton with radial chirality, hereafter called radial vortex. It has a noninteger Skyrmion number S (0.5<|S|<1) due to both the vortex core polarity and the magnetization tilting induced by the IDMI boundary conditions. Micromagnetic simulations predict that a magnetoresistive memory based on the radial vortex state in both free and polarizer layers can be efficiently switched by a threshold current density smaller than 10^{6} A/cm^{2}. The switching processes occur via the nucleation of topologically connected vortices and vortex-antivortex pairs, followed by spin-wave emissions due to vortex-antivortex annihilations.
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Affiliation(s)
- G Siracusano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - R Tomasello
- Department of Engineering, Polo Scientifico Didattico di Terni, University of Perugia, I-50100 Terni, Italy
| | - A Giordano
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
| | - V Puliafito
- Department of Engineering, University of Messina, I-98166 Messina, Italy
| | - B Azzerboni
- Department of Engineering, University of Messina, I-98166 Messina, Italy
| | - O Ozatay
- Department of Physics, Bogazici University, 34342 Bebek/Istanbul, Turkey
| | - M Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, via E. Orabona 4, I-70125 Bari, Italy
| | - G Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, I-98166 Messina, Italy
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18
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Fang B, Carpentieri M, Hao X, Jiang H, Katine JA, Krivorotov IN, Ocker B, Langer J, Wang KL, Zhang B, Azzerboni B, Amiri PK, Finocchio G, Zeng Z. Giant spin-torque diode sensitivity in the absence of bias magnetic field. Nat Commun 2016; 7:11259. [PMID: 27052973 PMCID: PMC4829691 DOI: 10.1038/ncomms11259] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [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: 10/15/2015] [Accepted: 03/07/2016] [Indexed: 11/10/2022] Open
Abstract
Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors.
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Affiliation(s)
- Bin Fang
- Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, China
| | - Mario Carpentieri
- Department of Electrical and Information Engineering, Polytechnic of Bari, Bari 70125, Italy
| | - Xiaojie Hao
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Hongwen Jiang
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Jordan A Katine
- HGST Inc, 3403 Yerba Buena Road, San Jose, California 95135, USA
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | | | | | - Kang L Wang
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Baoshun Zhang
- Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, China
| | - Bruno Azzerboni
- Department of Engineering, University of Messina, Messina 98166, Italy
| | - Pedram Khalili Amiri
- Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA
| | - Giovanni Finocchio
- Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina, Messina 98166, Italy
| | - Zhongming Zeng
- Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Ruoshui Road 398, Suzhou 215123, China
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19
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Carpentieri M, Tomasello R, Zivieri R, Finocchio G. Topological, non-topological and instanton droplets driven by spin-transfer torque in materials with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya Interaction. Sci Rep 2015; 5:16184. [PMID: 26548898 PMCID: PMC4637900 DOI: 10.1038/srep16184] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [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: 07/13/2015] [Accepted: 10/12/2015] [Indexed: 11/08/2022] Open
Abstract
The interfacial Dzyaloshinskii-Moriya Interaction can modify the topology of droplets excited by a localized spin-polarized current. Here, we show that, in addition to the stationary droplet excitations with skyrmion number either one (topological) or zero (non-topological), there exists, for a fixed current, an excited mode with a non-stationary time behavior. We call this mode "instanton droplet", which is characterized by time domain transitions of the skyrmion number. These transitions are coupled to an emission of incoherent spin-waves that can be observed in the frequency domain as a source of noise. Our results are interesting from a fundamental point of view to study spin-wave emissions due to a topological transition in current-driven systems, and could open the route for experiments based on magnetoresistance effect for the design of a further generation of nanoscale microwave oscillators.
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Affiliation(s)
- Mario Carpentieri
- Department of Electrical and Information Engineering, Politecnico di Bari, via E. Orabona 4, I-70125 Bari, Italy
| | - Riccardo Tomasello
- Department of Computer Science, Modelling, Electronics and System Science, University of Calabria, via P. Bucci 41C, I-87036, Rende (CS), Italy
| | - Roberto Zivieri
- Department of Electrical and Information Engineering, Politecnico di Bari, via E. Orabona 4, I-70125 Bari, Italy
- Department of Physics and Earth Sciences and CNISM Unit of Ferrara, University of Ferrara, Ferrara, via Saragat 1, I-44122, Ferrara, Italy
| | - Giovanni Finocchio
- Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, c.da di Dio, I-98166, Messina, Italy
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Milardi D, Gaeta M, Marino S, Arrigo A, Vaccarino G, Mormina E, Rizzo G, Milazzo C, Finocchio G, Baglieri A, Anastasi G, Quartarone A. Basal ganglia network by constrained spherical deconvolution: a possible cortico-pallidal pathway? Mov Disord 2014; 30:342-9. [PMID: 25156805 DOI: 10.1002/mds.25995] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 12/26/2022] Open
Abstract
In the recent past, basal ganglia circuitry was simplified as represented by the direct and indirect pathways and by hyperdirect pathways. Based on data from animal studies, we hypothesized a fourth pathway, the cortico-pallidal, pathway, that complements the hyperdirect pathway to the subthalamus. Ten normal brains were analyzed by using the high angular resolution diffusion imaging-constrained spherical deconvolution (CSD)-based technique. The study was performed with a 3T magnetic resonance imaging (MRI) scanner (Achieva, Philips Healthcare, Best, Netherlands); by using a 32-channel SENSE head coil. We showed that CSD is a powerful technique that allows a fine evaluation of both the long and small tracts between cortex and basal ganglia, including direct, indirect, and hyperdirect pathways. In addition, a pathway directly connecting the cortex to the globus pallidus was seen. Our results confirm that the CSD tractography is a valuable technique allowing a reliable reconstruction of small- and long-fiber pathways in brain regions with multiple fiber orientations, such as basal ganglia. This could open a future scenario in which CSD could be used to focally target with deep brain stimulation (DBS) the small bundles within the basal ganglia loops.
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Affiliation(s)
- Demetrio Milardi
- Department of Biomedical Sciences and Morphological and Functional Images, University of Messina, Italy; IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
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21
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Milardi D, Bramanti P, Milazzo C, Finocchio G, Arrigo A, Santoro G, Trimarchi F, Quartarone A, Anastasi G, Gaeta M. Cortical and subcortical connections of the human claustrum revealed in vivo by constrained spherical deconvolution tractography. Cereb Cortex 2013; 25:406-14. [PMID: 24014669 DOI: 10.1093/cercor/bht231] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The claustrum is a thin layer of gray matter that is at the center of an active scientific debate. Recently, Constrained Spherical Deconvolution (CSD) tractography has proved to be an extraordinary tool allowing to track white matter fibers from cortex to cortical and subcortical targets with subvoxel resolution. The aim of this study was to evaluate claustral connectivity in the human brain. Ten normal brains were analyzed by using the High Angular Resolution Diffusion Imaging CSD-based technique. Tractography revealed 4 groups of white matter fibers connecting the claustrum with the brain cortex: Anterior, posterior, superior, and lateral. The anterior and posterior cortico-claustral tracts connected the claustrum to prefrontal cortex and visual areas. The superior tract linked the claustrum with sensory-motor areas, while the lateral pathway connected the claustrum to the auditory cortex. In addition, we demonstrated a claustral medial pathway connecting the claustrum with the basal ganglia, specifically with caudate nucleus, putamen, and globus pallidus. An interesting and exciting new finding was the demonstration of a bilateral connection between claustrum and contralateral cortical areas and a well-represented interclaustral communication with interconnection bundles interspersed within the bulk of the trunk of the corpus callosum. The physiological and pathophysiological relevance of these findings are discussed.
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Affiliation(s)
- Demetrio Milardi
- Department of Biomedical Sciences and Morphological and Functional Imaging, IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
| | | | - Carmelo Milazzo
- Department of Biomedical Sciences and Morphological and Functional Imaging
| | | | - Alessandro Arrigo
- Department of Biomedical Sciences and Morphological and Functional Imaging
| | - Giuseppe Santoro
- Department of Biomedical Sciences and Morphological and Functional Imaging, IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
| | - Fabio Trimarchi
- Department of Biomedical Sciences and Morphological and Functional Imaging, IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
| | - Angelo Quartarone
- Department Electronic Engineering, Chemistry and Industrial Engineering, Department of Neurosciences, University of Messina, Messina, Italy and
| | - Giuseppe Anastasi
- Department of Biomedical Sciences and Morphological and Functional Imaging, IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
| | - Michele Gaeta
- Department of Biomedical Sciences and Morphological and Functional Imaging, IRCCS Centro Neurolesi Bonino Pulejo, Messina, Italy
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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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Zeng Z, Amiri PK, Krivorotov IN, Zhao H, Finocchio G, Wang JP, Katine JA, Huai Y, Langer J, Galatsis K, Wang KL, Jiang H. High-power coherent microwave emission from magnetic tunnel junction nano-oscillators with perpendicular anisotropy. ACS Nano 2012; 6:6115-6121. [PMID: 22663148 DOI: 10.1021/nn301222v] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The excitation of the steady-state precessions of magnetization opens a new way for nanoscale microwave oscillators by exploiting the transfer of spin angular momentum from a spin-polarized current to a ferromagnet, referred to as spin-transfer nano-oscillators (STNOs). For STNOs to be practical, however, their relatively low output power and their relatively large line width must be improved. Here we demonstrate that microwave signals with maximum measured power of 0.28 μW and simultaneously narrow line width of 25 MHz can be generated from CoFeB-MgO-based magnetic tunnel junctions having an in-plane magnetized reference layer and a free layer with strong perpendicular anisotropy. Moreover, the generation efficiency is substantially higher than previously reported STNOs. The results will be of importance for the design of nanoscale alternatives to traditional silicon oscillators used in radio frequency integrated circuits.
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Affiliation(s)
- Zhongming Zeng
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States.
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Bonetti S, Tiberkevich V, Consolo G, Finocchio G, Muduli P, Mancoff F, Slavin A, Akerman J. Experimental evidence of self-localized and propagating spin wave modes in obliquely magnetized current-driven nanocontacts. Phys Rev Lett 2010; 105:217204. [PMID: 21231348 DOI: 10.1103/physrevlett.105.217204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Revised: 05/28/2010] [Indexed: 05/30/2023]
Abstract
Through detailed experimental studies of the angular dependence of spin wave excitations in nanocontact-based spin-torque oscillators, we demonstrate that two distinct spin wave modes can be excited, with different frequency, threshold currents, and frequency tunability. Using analytical theory and micromagnetic simulations we identify one mode as an exchange-dominated propagating spin wave, and the other as a self-localized nonlinear spin wave bullet. Wavelet-based analysis of the simulations indicates that the apparent simultaneous excitation of both modes results from rapid mode hopping induced by the Oersted field.
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Affiliation(s)
- Stefano Bonetti
- Materials Physics, Royal Institute of Technology, Electrum 229, 164 40 Kista, Sweden.
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Cui YT, Finocchio G, Wang C, Katine JA, Buhrman RA, Ralph DC. Single-shot time-domain studies of spin-torque-driven switching in magnetic tunnel junctions. Phys Rev Lett 2010; 104:097201. [PMID: 20367007 DOI: 10.1103/physrevlett.104.097201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Indexed: 05/29/2023]
Abstract
We report single-shot measurements of resistance versus time for thermally assisted spin-torque switching in magnetic tunnel junctions. We achieve the sensitivity to resolve the magnetic dynamics prior to as well as during switching, yielding detailed views of switching modes and variations between events. Analyses of individual traces allow measurements of coherence times, nonequilibrium excitation spectra, and variations in magnetization precession amplitude. We find that with a small in-plane hard-axis magnetic field the switching dynamics are more spatially coherent than for a zero field.
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Affiliation(s)
- Y-T Cui
- Cornell University, Ithaca, New York 14853, USA
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Azzerboni B, Finocchio G, Ipsale M, La Foresta F, Morabito FC. A New Approach to Detection of Muscle Activation by Independent Component Analysis and Wavelet Transform. ACTA ACUST UNITED AC 2002. [DOI: 10.1007/3-540-45808-5_11] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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