1
|
Stephen GM, Hanbicki AT, Schumann T, Robinson JT, Goyal M, Stemmer S, Friedman AL. Room-Temperature Spin Transport in Cd 3As 2. ACS NANO 2021; 15:5459-5466. [PMID: 33705102 DOI: 10.1021/acsnano.1c00154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
As the need for ever greater transistor density increases, the commensurate decrease in device size approaches the atomic limit, leading to increased energy loss and leakage currents, reducing energy efficiencies. Alternative state variables, such as electronic spin rather than electronic charge, have the potential to enable more energy-efficient and higher performance devices. These spintronic devices require materials capable of efficiently harnessing the electron spin. Here we show robust spin transport in Cd3As2 films up to room temperature. We demonstrate a nonlocal spin valve switch from this material, as well as inverse spin Hall effect measurements yielding spin Hall angles as high as θSH = 1.5 and spin diffusion lengths of 10-40 μm. Long spin-coherence lengths with efficient charge-to-spin conversion rates and coherent spin transport up to room temperature, as we show here in Cd3As2, are enabling steps toward realizing actual spintronic devices.
Collapse
Affiliation(s)
- Gregory M Stephen
- Laboratory for Physical Sciences, 8050 Greenmead Drive, College Park, Maryland 20740, United States
| | - Aubrey T Hanbicki
- Laboratory for Physical Sciences, 8050 Greenmead Drive, College Park, Maryland 20740, United States
| | - Timo Schumann
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Jeremy T Robinson
- Electronics Science and Technology Division, Naval Research Laboratory, 4555 Overlook Avenue, S.W., Washington, D.C. 20375, United States
| | - Manik Goyal
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Susanne Stemmer
- Materials Department, University of California, Santa Barbara, California 93106-5050, United States
| | - Adam L Friedman
- Laboratory for Physical Sciences, 8050 Greenmead Drive, College Park, Maryland 20740, United States
| |
Collapse
|
2
|
Serrano IG, Panda J, Denoel F, Vallin Ö, Phuyal D, Karis O, Kamalakar MV. Two-Dimensional Flexible High Diffusive Spin Circuits. NANO LETTERS 2019; 19:666-673. [PMID: 30632370 DOI: 10.1021/acs.nanolett.8b03520] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Owing to their unprecedented electronic properties, graphene and two-dimensional (2D) crystals have brought fresh opportunities for advances in planar spintronic devices. Graphene is an ideal medium for spin transport while being an exceptionally resilient material for flexible nanoelectronics. However, these extraordinary traits have never been combined to create flexible graphene spin circuits. Realizing such circuits could lead to bendable strain-spin sensors, as well as a unique platform to explore pure spin current based operations and low-power 2D flexible nanoelectronics. Here, we demonstrate graphene spin circuits on flexible substrates for the first time. Despite the rough topography of the flexible substrates, these circuits prepared with chemical vapor deposited monolayer graphene reveal an efficient room temperature spin transport with distinctively large spin diffusion coefficients ∼0.2 m2 s-1. Compared to earlier graphene devices on Si/SiO2 substrates, such values are up to 20 times larger, leading to one order higher spin signals and an enhanced spin diffusion length ∼10 μm in graphene-based nonlocal spin valves fabricated using industry standard systems. This high performance arising out of a characteristic substrate terrain shows promise of a scalable and flexible platform towards flexible 2D spintronics. Our innovation is a key step for the exploration of strain-dependent 2D spin phenomena and paves the way for flexible graphene spin memory-logic units and planar spin sensors.
Collapse
Affiliation(s)
- I G Serrano
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - J Panda
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Fernand Denoel
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Örjan Vallin
- Department of Engineering Sciences , Uppsala University , Box 534, SE 751 21 , Uppsala , Sweden
| | - Dibya Phuyal
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - Olof Karis
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| | - M Venkata Kamalakar
- Department of Physics and Astronomy , Uppsala University , Box 516, SE 751 20 , Uppsala , Sweden
| |
Collapse
|
3
|
Whitener KE, Robinson JT, Sheehan PE. Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13749-13756. [PMID: 29120637 DOI: 10.1021/acs.langmuir.7b03596] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We show that dehydrogenation of hydrogenated graphene proceeds much more slowly for bilayer systems than for single layer systems. We observe that an underlayer of either pristine or hydrogenated graphene will protect an overlayer of hydrogenated graphene against a number of chemical oxidants, thermal dehydrogenation, and degradation in an ambient environment over extended periods of time. Chemical protection depends on the ease of oxidant intercalation, with good intercalants such as Br2 demonstrating much higher reactivity than poor intercalants such as 1,2-dichloro-4,5-dicyanonbenzoquinone (DDQ). Additionally, the rate of dehydrogenation of hydrogenated graphene at 300 °C in H2/Ar was reduced by a factor of roughly 10 in the presence of a protective underlayer of graphene or hydrogenated graphene. Finally, the slow dehydrogenation of hydrogenated graphene in air at room temperature, which is normally apparent after a week, could be completely eliminated in samples with protective underlayers over the course of 39 days. Such protection will be critical for ensuring the long-term stability of devices made from functionalized graphene.
Collapse
Affiliation(s)
- Keith E Whitener
- Chemistry Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Jeremy T Robinson
- Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Paul E Sheehan
- Chemistry Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| |
Collapse
|
4
|
Chronopoulos DD, Bakandritsos A, Pykal M, Zbořil R, Otyepka M. Chemistry, properties, and applications of fluorographene. APPLIED MATERIALS TODAY 2017; 9:60-70. [PMID: 29238741 PMCID: PMC5721099 DOI: 10.1016/j.apmt.2017.05.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 05/23/2023]
Abstract
Fluorographene, formally a two-dimensional stoichiometric graphene derivative, attracted remarkable attention of the scientific community due to its extraordinary physical and chemical properties. We overview the strategies for the preparation of fluorinated graphene derivatives, based on top-down and bottom-up approaches. The physical and chemical properties of fluorographene, which is considered as one of the thinnest insulators with a wide electronic band gap, are presented. Special attention is paid to the rapidly developing chemistry of fluorographene, which was advanced in the last few years. The unusually high reactivity of fluorographene, which can be chemically considered perfluorinated hydrocarbon, enables facile and scalable access to a wide portfolio of graphene derivatives, such as graphene acid, cyanographene and allyl-graphene. Finally, we summarize the so far reported applications of fluorographene and fluorinated graphenes, spanning from sensing and bioimaging to separation, electronics and energy technologies.
Collapse
|
5
|
|
6
|
Large room temperature spin-to-charge conversion signals in a few-layer graphene/Pt lateral heterostructure. Nat Commun 2017; 8:661. [PMID: 28939841 PMCID: PMC5610249 DOI: 10.1038/s41467-017-00563-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 07/10/2017] [Indexed: 11/15/2022] Open
Abstract
Electrical generation and detection of pure spin currents without the need of magnetic materials are key elements for the realization of full electrically controlled spintronic devices. In this framework, achieving a large spin-to-charge conversion signal is crucial, as considerable outputs are needed for plausible applications. Unfortunately, the values obtained so far have been rather low. Here we exploit the spin Hall effect by using Pt, a non-magnetic metal with strong spin-orbit coupling, to generate and detect pure spin currents in a few-layer graphene channel. Furthermore, the outstanding properties of graphene, with long-distance spin transport and higher electrical resistivity than metals, allow us to achieve in our graphene/Pt lateral heterostructures the largest spin-to-charge output voltage at room temperature reported so far in the literature. Our approach opens up exciting opportunities towards the implementation of spin-orbit-based logic circuits and all electrical control of spin information without magnetic field. Spintronic devices with full electrical control rely on electrical generation and detection of spin currents in the absence of magnetic materials. Here, the authors use Pt, a non-magnetic metal, to generate and detect pure spin currents in a few-layer graphene channel, achieving a remarkable spin-to-charge voltage signal at room temperature.
Collapse
|
7
|
Electrical gate control of spin current in van der Waals heterostructures at room temperature. Nat Commun 2017; 8:16093. [PMID: 28677673 PMCID: PMC5504284 DOI: 10.1038/ncomms16093] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/25/2017] [Indexed: 12/23/2022] Open
Abstract
Two-dimensional (2D) crystals offer a unique platform due to their remarkable and contrasting spintronic properties, such as weak spin–orbit coupling (SOC) in graphene and strong SOC in molybdenum disulfide (MoS2). Here we combine graphene and MoS2 in a van der Waals heterostructure (vdWh) to demonstrate the electric gate control of the spin current and spin lifetime at room temperature. By performing non-local spin valve and Hanle measurements, we unambiguously prove the gate tunability of the spin current and spin lifetime in graphene/MoS2 vdWhs at 300 K. This unprecedented control over the spin parameters by orders of magnitude stems from the gate tuning of the Schottky barrier at the MoS2/graphene interface and MoS2 channel conductivity leading to spin dephasing in high-SOC material. Our findings demonstrate an all-electrical spintronic device at room temperature with the creation, transport and control of the spin in 2D materials heterostructures, which can be key building blocks in future device architectures. Two-dimensional materials are unique to build heterostructures with contrasting spintronic properties. Here, Dankert and Dash utilize a van der Waals heterostructure with graphene and MoS2 to demonstrate an all-electrical device for creation, transport and control of the spin current up to room temperature.
Collapse
|
8
|
Feng YP, Shen L, Yang M, Wang A, Zeng M, Wu Q, Chintalapati S, Chang CR. Prospects of spintronics based on 2D materials. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1313] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yuan Ping Feng
- Department of Physics; National University of Singapore; Singapore
- Centre for Advanced Two-dimensional Materials; National University of Singapore; Singapore
| | - Lei Shen
- Department of Mechanical Engineering; National University of Singapore; Singapore
- Engineering Science Programme; National University of Singapore; Singapore
| | - Ming Yang
- Institute of Materials Science and Engineering; A*STAR; Singapore
| | - Aizhu Wang
- Department of Physics; National University of Singapore; Singapore
- Department of Electrical and Computer Engineering; National University of Singapore; Singapore
| | | | - Qingyun Wu
- Department of Materials Science and Engineering; National University of Singapore; Singapore
| | - Sandhya Chintalapati
- Centre for Advanced Two-dimensional Materials; National University of Singapore; Singapore
| | | |
Collapse
|
9
|
Cobas ED, van 't Erve OMJ, Cheng SF, Culbertson JC, Jernigan GG, Bussman K, Jonker BT. Room-Temperature Spin Filtering in Metallic Ferromagnet-Multilayer Graphene-Ferromagnet Junctions. ACS NANO 2016; 10:10357-10365. [PMID: 27806204 DOI: 10.1021/acsnano.6b06092] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report room-temperature negative magnetoresistance in ferromagnet-graphene-ferromagnet (FM|Gr|FM) junctions with minority spin polarization exceeding 80%, consistent with predictions of strong minority spin filtering. We fabricated arrays of such junctions via chemical vapor deposition of multilayer graphene on lattice-matched single-crystal NiFe(111) films and standard photolithographic patterning and etching techniques. The junctions exhibit metallic transport behavior, low resistance, and the negative magnetoresistance characteristic of a minority spin filter interface throughout the temperature range 10 to 300 K. We develop a device model to incorporate the predicted spin filtering by explicitly treating a metallic minority spin channel with spin current conversion and a tunnel barrier majority spin channel and extract spin polarization of at least 80% in the graphene layer in our structures. The junctions also show antiferromagnetic coupling, consistent with several recent predictions. The methods and findings are relevant to fast-readout low-power magnetic random access memory technology, spin logic devices, and low-power magnetic field sensors.
Collapse
Affiliation(s)
- Enrique D Cobas
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - Olaf M J van 't Erve
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - Shu-Fan Cheng
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - James C Culbertson
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - Glenn G Jernigan
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - Konrad Bussman
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| | - Berend T Jonker
- Naval Research Laboratory , 4555 Overlook Avenue SW, Washington D.C. 20375, United States
| |
Collapse
|
10
|
Drögeler M, Franzen C, Volmer F, Pohlmann T, Banszerus L, Wolter M, Watanabe K, Taniguchi T, Stampfer C, Beschoten B. Spin Lifetimes Exceeding 12 ns in Graphene Nonlocal Spin Valve Devices. NANO LETTERS 2016; 16:3533-9. [PMID: 27210240 DOI: 10.1021/acs.nanolett.6b00497] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We show spin lifetimes of 12.6 ns and spin diffusion lengths as long as 30.5 μm in single layer graphene nonlocal spin transport devices at room temperature. This is accomplished by the fabrication of Co/MgO-electrodes on a Si/SiO2 substrate and the subsequent dry transfer of a graphene-hBN-stack on top of this electrode structure where a large hBN flake is needed in order to diminish the ingress of solvents along the hBN-to-substrate interface. Interestingly, long spin lifetimes are observed despite the fact that both conductive scanning force microscopy and contact resistance measurements reveal the existence of conducting pinholes throughout the MgO spin injection/detection barriers. Compared to previous devices, we observe an enhancement of the spin lifetime in single layer graphene by a factor of 6. We demonstrate that the spin lifetime does not depend on the contact resistance area products when comparing all bottom-up devices indicating that spin absorption at the contacts is not the predominant source for spin dephasing.
Collapse
Affiliation(s)
- Marc Drögeler
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Christopher Franzen
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Frank Volmer
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Tobias Pohlmann
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Luca Banszerus
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Maik Wolter
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Christoph Stampfer
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Bernd Beschoten
- 2nd Institute of Physics and JARA-FIT, RWTH Aachen University , 52074 Aachen, Germany
| |
Collapse
|
11
|
Whitener KE, Lee WK, Bassim ND, Stroud RM, Robinson JT, Sheehan PE. Transfer of Chemically Modified Graphene with Retention of Functionality for Surface Engineering. NANO LETTERS 2016; 16:1455-1461. [PMID: 26784372 DOI: 10.1021/acs.nanolett.5b05073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Single-layer graphene chemically reduced by the Birch process delaminates from a Si/SiOx substrate when exposed to an ethanol/water mixture, enabling transfer of chemically functionalized graphene to arbitrary substrates such as metals, dielectrics, and polymers. Unlike in previous reports, the graphene retains hydrogen, methyl, and aryl functional groups during the transfer process. This enables one to functionalize the receiving substrate with the properties of the chemically modified graphene (CMG). For instance, magnetic force microscopy shows that the previously reported magnetic properties of partially hydrogenated graphene remain after transfer. We also transfer hydrogenated graphene from its copper growth substrate to a Si/SiOx wafer and thermally dehydrogenate it to demonstrate a polymer- and etchant-free graphene transfer for potential use in transmission electron microscopy. Finally, we show that the Birch reduction facilitates delamination of CMG by weakening van der Waals forces between graphene and its substrate.
Collapse
Affiliation(s)
- Keith E Whitener
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Woo-Kyung Lee
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Nabil D Bassim
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Rhonda M Stroud
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Jeremy T Robinson
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Paul E Sheehan
- Chemistry Division, ‡Materials Science and Technology Division, and §Electronic Science and Technology Division, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| |
Collapse
|
12
|
Canto B, Gouvea CP, Archanjo BS, Schmidt JE, Baptista DL. On the Structural and Chemical Characteristics of Co/Al2O3/graphene Interfaces for Graphene Spintronic Devices. Sci Rep 2015; 5:14332. [PMID: 26395513 PMCID: PMC4585803 DOI: 10.1038/srep14332] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 08/25/2015] [Indexed: 11/25/2022] Open
Abstract
We report a detailed investigation of the structural and chemical characteristics of thin evaporated Al2O3 tunnel barriers of variable thickness grown onto single-layer graphene sheets. Advanced electron microscopy and spectrum-imaging techniques were used to investigate the Co/Al2O3/graphene/SiO2 interfaces. Direct observation of pinhole contacts was achieved using FIB cross-sectional lamellas. Spatially resolved EDX spectrum profiles confirmed the presence of direct point contacts between the Co layer and the graphene. The high surface diffusion properties of graphene led to cluster-like Al2O3 film growth, limiting the minimal possible thickness for complete barrier coverage onto graphene surfaces using standard Al evaporation methods. The results indicate a minimum thickness of nominally 3 nm Al2O3, resulting in a 0.6 nm rms rough film with a maximum thickness reaching 5 nm.
Collapse
Affiliation(s)
- Bárbara Canto
- Instituto de Física, PPGFis, PPGMicro, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
| | - Cristol P. Gouvea
- Divisão de Metrologia de Materiais, INMETRO, Duque de Caxias, 25250-020, RJ, Brazil
| | - Bráulio S. Archanjo
- Divisão de Metrologia de Materiais, INMETRO, Duque de Caxias, 25250-020, RJ, Brazil
| | - João E. Schmidt
- Instituto de Física, PPGFis, PPGMicro, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
| | - Daniel L. Baptista
- Instituto de Física, PPGFis, PPGMicro, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
| |
Collapse
|