1
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Jiang Y, de Jong EJ, van de Sande V, Gazibegovic S, Badawy G, Bakkers EPAM, Frolov SM. Hysteretic magnetoresistance in nanowire devices due to stray fields induced by micromagnets. NANOTECHNOLOGY 2021; 32:095001. [PMID: 33142271 DOI: 10.1088/1361-6528/abc70f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We study hysteretic magnetoresistance in InSb nanowires due to stray magnetic fields from CoFe micromagnets. Devices without any ferromagnetic components show that the magnetoresistance of InSb nanowires commonly exhibits either a local maximum or local minimum at zero magnetic field. Switching of microstrip magnetizations then results in positive or negative hysteretic dependence as conductance maxima or minima shift with respect to the global external field. Stray fields are found to be in the range of tens of millitesla, comparable to the scale over which the nanowire magnetoresistance develops. We observe that the stray field signal is similar to that obtained in devices with ferromagnetic contacts (spin valves). We perform micromagnetic simulations which are in reasonable agreement with the experiment. The use of locally varying magnetic fields may bring new ideas for Majorana circuits in which nanowire networks require control over field orientation at the nanoscale.
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Affiliation(s)
- Y Jiang
- University of Pittsburgh, Pittsburgh, PA 15260, United States of America
| | - E J de Jong
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - V van de Sande
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - S Gazibegovic
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - G Badawy
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - E P A M Bakkers
- Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
| | - S M Frolov
- University of Pittsburgh, Pittsburgh, PA 15260, United States of America
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2
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Mikulics M, Sofer Z, Winden A, Trellenkamp S, Förster B, Mayer J, Hardtdegen HH. Nano-LED induced chemical reactions for structuring processes. NANOSCALE ADVANCES 2020; 2:5421-5427. [PMID: 36132052 PMCID: PMC9418560 DOI: 10.1039/d0na00851f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/19/2020] [Indexed: 06/12/2023]
Abstract
We present a structuring technique based on the initialization of chemical reactions by an array of nano-LEDs which is used in the near-field as well as in the far-field regime. In the near-field regime, we demonstrate first results with the nano-LED array for lithography using the photoresist DiazoNaphthoQuinone-(DNQ)-sulfonate for the fabrication of holes in the resist down to ∼75 nanometres in diameter. In contrast, the nano-LEDs can also be employed in the far-field regime to expose thin films of the monomer bisphenol A-glycidyl methacrylate (Bis-GMA) and to initialize polymerization locally. Photosensitive films were patterned and spherical cone-shaped three dimensional objects with diameters ranging from ∼480 nm up to 20 micrometres were obtained. The modification in the material as a result of the photochemical reaction induced i.e. by polymerization was confirmed by Raman spectroscopy. This structuring maskless technique has the potential to induce substantial changes in photosensitive molecules and to produce the desired structures from the tens of microns down to the nanometre scale.
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Affiliation(s)
- Martin Mikulics
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
| | - Zdenĕk Sofer
- Department of Inorganic Chemistry, Institute of Chemical Technology Technická 5 Prague 6 Czech Republic
| | | | - Stefan Trellenkamp
- Helmholtz Nanoelectronic Facility (HNF), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
| | - Beate Förster
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
- Ernst Ruska Zentrum (ER-C-1), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
| | - Joachim Mayer
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
| | - Hilde Helen Hardtdegen
- Ernst Ruska Zentrum (ER-C-2), Forschungszentrum Jülich GmbH D-52425 Jülich Germany
- Jülich-Aachen Research Alliance, JARA, Fundamentals of Future Information Technology 52425 Jülich Germany
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3
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Chen S, Huang Y, Visser D, Anand S, Buyanova IA, Chen WM. Room-temperature polarized spin-photon interface based on a semiconductor nanodisk-in-nanopillar structure driven by few defects. Nat Commun 2018; 9:3575. [PMID: 30177701 PMCID: PMC6120900 DOI: 10.1038/s41467-018-06035-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 08/13/2018] [Indexed: 11/24/2022] Open
Abstract
Owing to their superior optical properties, semiconductor nanopillars/nanowires in one-dimensional (1D) geometry are building blocks for nano-photonics. They also hold potential for efficient polarized spin-light conversion in future spin nano-photonics. Unfortunately, spin generation in 1D systems so far remains inefficient at room temperature. Here we propose an approach that can significantly enhance the radiative efficiency of the electrons with the desired spin while suppressing that with the unwanted spin, which simultaneously ensures strong spin and light polarization. We demonstrate high optical polarization of 20%, inferring high electron spin polarization up to 60% at room temperature in a 1D system based on a GaNAs nanodisk-in-GaAs nanopillar structure, facilitated by spin-dependent recombination via merely 2–3 defects in each nanodisk. Our approach points to a promising direction for realization of an interface for efficient spin-photon quantum information transfer at room temperature—a key element for future spin-photonic applications. Room-temperature spin-generation in 1D systems like semiconductor nanopillars is typically inefficient. Here, the authors demonstrate an approach to achieve efficient spin polarization, even in the absence of a magnetic field, by selectively enhancing the radiative efficiency of one spin direction.
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Affiliation(s)
- Shula Chen
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden.
| | - Yuqing Huang
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden
| | - Dennis Visser
- Department of Applied Physics, KTH Royal Institute of Technology, SE16440, Kista, Stockholm, Sweden
| | - Srinivasan Anand
- Department of Applied Physics, KTH Royal Institute of Technology, SE16440, Kista, Stockholm, Sweden
| | - Irina A Buyanova
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden
| | - Weimin M Chen
- Department of Physics, Chemistry and Biology, Linköping University, SE58183, Linköping, Sweden.
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4
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Kountouriotis K, Barreda JL, Keiper TD, Zhang M, Xiong P. Electrical Spin Injection and Detection in Silicon Nanowires with Axial Doping Gradient. NANO LETTERS 2018; 18:4386-4395. [PMID: 29898367 DOI: 10.1021/acs.nanolett.8b01423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interest in spin transport in nanoscopic semiconductor channels is driven by both the inevitable miniaturization of spintronics devices toward nanoscale and the rich spin-dependent physics the quantum confinement engenders. For such studies, the all-important issue of the ferromagnet/semiconductor (FM/SC) interface becomes even more critical at nanoscale. Here we elucidate the effects of the FM/SC interface on electrical spin injection and detection at nanoscale dimensions, utilizing a unique type of Si nanowires (NWs) with an inherent axial doping gradient. Two-terminal and nonlocal four-terminal lateral spin-valve measurements were performed using different combinations from a series of FM contacts positioned along the same NW. The data are analyzed with a general model of spin accumulation in a normal channel under electrical spin injection from a FM, which reveals a distinct correlation of decreasing spin-valve signal with increasing injector junction resistance. The observation is attributed to the diminishing contribution of the d-electrons in the FM to the injected current spin polarization with increasing Schottky barrier width. The results demonstrate that there is a window of interface parameters for optimal spin injection efficiency and current spin polarization, which provides important design guidelines for nanospintronic devices with quasi-one-dimensional semiconductor channels.
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Affiliation(s)
| | - Jorge L Barreda
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
| | - Timothy D Keiper
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
| | - Mei Zhang
- Department of Industrial and Manufacturing Engineering, College of Engineering , Florida A&M University-Florida State University (FAMU-FSU) , Tallahassee , Florida 32310 , United States
| | - Peng Xiong
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
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5
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Park TE, Park YH, Lee JM, Kim SW, Park HG, Min BC, Kim HJ, Koo HC, Choi HJ, Han SH, Johnson M, Chang J. Large spin accumulation and crystallographic dependence of spin transport in single crystal gallium nitride nanowires. Nat Commun 2017; 8:15722. [PMID: 28569767 PMCID: PMC5461503 DOI: 10.1038/ncomms15722] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 04/24/2017] [Indexed: 11/09/2022] Open
Abstract
Semiconductor spintronics is an alternative to conventional electronics that offers devices with high performance, low power and multiple functionality. Although a large number of devices with mesoscopic dimensions have been successfully demonstrated at low temperatures for decades, room-temperature operation still needs to go further. Here we study spin injection in single-crystal gallium nitride nanowires and report robust spin accumulation at room temperature with enhanced spin injection polarization of 9%. A large Overhauser coupling between the electron spin accumulation and the lattice nuclei is observed. Finally, our single-crystal gallium nitride samples have a trigonal cross-section defined by the (001), () and () planes. Using the Hanle effect, we show that the spin accumulation is significantly different for injection across the (001) and () (or ()) planes. This provides a technique for increasing room temperature spin injection in mesoscopic systems.
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Affiliation(s)
- Tae-Eon Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Youn Ho Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Jong-Min Lee
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Sung Wook Kim
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Hee Gyum Park
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
| | - Byoung-Chul Min
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
| | - Hyung-Jun Kim
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Hyun Cheol Koo
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Heon-Jin Choi
- Department of Materials Science and Engineering, Yonsei University, Seoul 03722, Korea
| | - Suk Hee Han
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea
| | - Mark Johnson
- Naval Research Laboratory, Washington, District Of Columbia 20375, USA
| | - Joonyeon Chang
- Center for Spintronics, Post-Si Semiconductor Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Korea.,Department of Nanomaterials Science and Engineering, Korea University of Science and Technology, Daejeon 34113, Korea
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6
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Signorello G, Sant S, Bologna N, Schraff M, Drechsler U, Schmid H, Wirths S, Rossell MD, Schenk A, Riel H. Manipulating Surface States of III-V Nanowires with Uniaxial Stress. NANO LETTERS 2017; 17:2816-2824. [PMID: 28383924 DOI: 10.1021/acs.nanolett.6b05098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
III-V compound semiconductors are indispensable materials for today's high-end electronic and optoelectronic devices and are being explored for next-generation transistor logic and quantum technologies. III-V surfaces and interfaces play the leading role in determining device performance, and therefore, methods to control their electronic properties have been developed. Typically, surface passivation studies demonstrated how to limit the density of surface states. Strain has been widely used to improve the electronic transport properties and optoelectronic properties of III-Vs, but the potential of this technology to modify the surface properties still remains to be explored. Here we show that uniaxial stress induces a shift in the energy of the surface states of III-V nanowires, modifying their electronic properties. We demonstrate this phenomenon by modulating the conductivity of InAs nanowires over 4 orders of magnitude with axial strain ranging between -2.5% in compression and 2.1% in tension. The band bending at the surface of the nanostructure is modified from accumulation to depletion reversibly and reproducibly. We provide evidence of this physical effect using a combination of electrical transport measurement, Raman spectroscopy, band-structure modeling, and technology computer aided design (TCAD) simulations. With this methodology, the deformation potentials for the surface states are quantified. These results reveal that strain technology can be used to shift surface states away from energy ranges in which device performance is negatively affected and represent a novel route to engineer the electronic properties of III-V devices.
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Affiliation(s)
- G Signorello
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - S Sant
- Integrated Systems Laboratory, Department of Electrical Engineering and Information Technology, ETH Zürich , 8092 Zürich, Switzerland
| | - N Bologna
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf, Switzerland
| | - M Schraff
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - U Drechsler
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - H Schmid
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - S Wirths
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
| | - M D Rossell
- Electron Microscopy Center, EMPA, Swiss Federal Laboratories for Materials Science and Technology , 8600 Dübendorf, Switzerland
| | - A Schenk
- Integrated Systems Laboratory, Department of Electrical Engineering and Information Technology, ETH Zürich , 8092 Zürich, Switzerland
| | - H Riel
- IBM Research - Zurich , 8803 Rüschlikon, Switzerland
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7
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Modepalli V, Jin MJ, Park J, Jo J, Kim JH, Baik JM, Seo C, Kim J, Yoo JW. Gate-Tunable Spin Exchange Interactions and Inversion of Magnetoresistance in Single Ferromagnetic ZnO Nanowires. ACS NANO 2016; 10:4618-4626. [PMID: 26964013 DOI: 10.1021/acsnano.6b00921] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrical control of ferromagnetism in semiconductor nanostructures offers the promise of nonvolatile functionality in future semiconductor spintronics. Here, we demonstrate a dramatic gate-induced change of ferromagnetism in ZnO nanowire (NW) field-effect transistors (FETs). Ferromagnetism in our ZnO NWs arose from oxygen vacancies, which constitute deep levels hosting unpaired electron spins. The magnetic transition temperature of the studied ZnO NWs was estimated to be well above room temperature. The in situ UV confocal photoluminescence (PL) study confirmed oxygen vacancy mediated ferromagnetism in the studied ZnO NW FET devices. Both the estimated carrier concentration and temperature-dependent conductivity reveal the studied ZnO NWs are at the crossover of the metal-insulator transition. In particular, gate-induced modulation of the carrier concentration in the ZnO NW FET significantly alters carrier-mediated exchange interactions, which causes even inversion of magnetoresistance (MR) from negative to positive values. Upon sweeping the gate bias from -40 to +50 V, the MRs estimated at 2 K and 2 T were changed from -11.3% to +4.1%. Detailed analysis on the gate-dependent MR behavior clearly showed enhanced spin splitting energy with increasing carrier concentration. Gate-voltage-dependent PL spectra of an individual NW device confirmed the localization of oxygen vacancy-induced spins, indicating that gate-tunable indirect exchange coupling between localized magnetic moments played an important role in the remarkable change of the MR.
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Affiliation(s)
- Vijayakumar Modepalli
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Mi-Jin Jin
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Jungmin Park
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Junhyeon Jo
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Ji-Hyun Kim
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Jeong Min Baik
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
| | - Changwon Seo
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - Jeongyong Kim
- Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
- Department of Energy Science, Sungkyunkwan University , Suwon 440-746, Republic of Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering-Low dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology , Ulsan 689-798, Republic of Korea
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8
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Hubmann J, Bauer B, Körner HS, Furthmeier S, Buchner M, Bayreuther G, Dirnberger F, Schuh D, Back CH, Zweck J, Reiger E, Bougeard D. Epitaxial Growth of Room-Temperature Ferromagnetic MnAs Segments on GaAs Nanowires via Sequential Crystallization. NANO LETTERS 2016; 16:900-905. [PMID: 26756067 DOI: 10.1021/acs.nanolett.5b03658] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We investigate the incorporation of manganese into self-catalyzed GaAs nanowires grown in molecular beam epitaxy. Our study reveals that Mn accumulates in the liquid Ga droplet and that no significant incorporation into the nanowire is observed. Using a sequential crystallization of the droplet, we then demonstrate a deterministic and epitaxial growth of MnAs segments at the nanowire tip. This technique may allow the seamless integration of multiple room-temperature ferromagnetic segments into GaAs nanowires with high-crystalline quality.
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Affiliation(s)
- Joachim Hubmann
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Benedikt Bauer
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Helmut S Körner
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Stephan Furthmeier
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Martin Buchner
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Günther Bayreuther
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Florian Dirnberger
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Dieter Schuh
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Christian H Back
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Josef Zweck
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Elisabeth Reiger
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
| | - Dominique Bougeard
- Institut für Experimentelle und Angewandte Physik, Universität Regensburg , D-93040 Regensburg, Germany
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9
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Wang Z, Pan D, Wang L, Wang T, Zhao B, Wu Y, Yang M, Xu X, Miao J, Zhao J, Jiang Y. Room-temperature spin transport in InAs nanowire lateral spin valve. RSC Adv 2016. [DOI: 10.1039/c6ra13516a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report room temperature spin transport in an InAs nanowire device. A large spin signal of 35 kΩ and long spin diffusion length of 1.9 μm are achieved. We believe that these results open a practical way to design InAs NW based spintronic devices.
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10
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Park YH, Ha R, Park TE, Kim SW, Seo D, Choi HJ. Magnetic In x Ga 1 - x N nanowires at room temperature using Cu dopant and annealing. NANOSCALE RESEARCH LETTERS 2015; 10:2501. [PMID: 26055472 PMCID: PMC4493842 DOI: 10.1186/1556-276x-10-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
Single-crystal, Cu-doped In x Ga1 - x N nanowires were grown on GaN/Al2O3 substrates via a vapor-liquid-solid (VLS) mechanism using Ni/Au bi-catalysts. The typical diameter of the Cu:In x Ga1 - x N nanowires was 80 to 150 nm, with a typical length of hundreds of micrometers. The as-grown nanowires exhibited diamagnetism. After annealing, the nanowires exhibited ferromagnetism with saturation magnetic moments higher than 0.8 μB (1 μB × 10(-24) Am(2)) per Cu atom at room temperature by the measurements using a superconducting quantum interference device (SQUID) magnetometer. X-ray absorption and X-ray magnetic circular dichroism spectra at Cu L 2,3-edges indicated that the doped Cu had a local magnetic moment and that its electronic configuration was mainly 3d (9). It possessed a small trivalent component, and thus, the n-type behavior of electrical property is measured at room temperature.
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Affiliation(s)
- Youn Ho Park
- />Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Ryong Ha
- />Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Tea-Eon Park
- />Spin Convergence Research Center, Korea Institute of Science and Technology (KIST), Seoul, 136-791 Republic of Korea
| | - Sung Wook Kim
- />Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Dongjea Seo
- />Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Heon-Jin Choi
- />Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
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11
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Kleftogiannis I, Tang CS, Cheng SJ. Finger-gate manipulated quantum transport in Dirac materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:205302. [PMID: 25950153 DOI: 10.1088/0953-8984/27/20/205302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate the quantum transport properties of multichannel nanoribbons made of materials described by the Dirac equation, under an in-plane magnetic field. In the low energy regime, positive and negative finger-gate potentials allow the electrons to make intra-subband transitions via hole-like or electron-like quasibound states (QBS), respectively, resulting in dips in the conductance. In the high energy regime, double dip structures in the conductance are found, attributed to spin-flip or spin-nonflip inter-subband transitions through the QBSs. Inverting the finger-gate polarity offers the possibility to manipulate the spin polarized electronic transport to achieve a controlled spin-switch.
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Affiliation(s)
- Ioannis Kleftogiannis
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan, Republic of China
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12
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Tang J, Wang KL. Electrical spin injection and transport in semiconductor nanowires: challenges, progress and perspectives. NANOSCALE 2015; 7:4325-4337. [PMID: 25686092 DOI: 10.1039/c4nr07611g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Spintronic devices are of fundamental interest for their nonvolatility and great potential for low-power electronics applications. The implementation of those devices usually favors materials with long spin lifetime and spin diffusion length. Recent spin transport studies on semiconductor nanowires have shown much longer spin lifetimes and spin diffusion lengths than those reported in bulk/thin films. In this paper, we have reviewed recent progress in the electrical spin injection and transport in semiconductor nanowires and drawn a comparison with that in bulk/thin films. In particular, the challenges and methods of making high-quality ferromagnetic tunneling and Schottky contacts on semiconductor nanowires as well as thin films are discussed. Besides, commonly used methods for characterizing spin transport have been introduced, and their applicability in nanowire devices are discussed. Moreover, the effect of spin-orbit interaction strength and dimensionality on the spin relaxation and hence the spin lifetime are investigated. Finally, for further device applications, we have examined several proposals of spinFETs and provided a perspective of future studies on semiconductor spintronics.
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Affiliation(s)
- Jianshi Tang
- Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA.
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13
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Tang CS, Tseng ST, Gudmundsson V, Cheng SJ. Double-finger-gate controlled spin-resolved resonant quantum transport in the presence of a Rashba-Zeeman gap. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:085801. [PMID: 25654308 DOI: 10.1088/0953-8984/27/8/085801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate double finger gate (DFG) controlled spin-resolved resonant transport properties in an n-type quantum channel with a Rashba-Zeeman (RZ) subband energy gap. By appropriately tuning the DFG in the strong Rashba coupling regime, resonant state structures in conductance can be found that are sensitive to the length of the DFG system. Furthermore, a hole-like bound state feature below the RZ gap and an electron-like quasi-bound state feature at the threshold of the upper spin branch can be found that is insensitive to the length of the DFG system.
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Affiliation(s)
- Chi-Shung Tang
- Department of Mechanical Engineering, National United University, Miaoli 36003, Taiwan
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Liu H, Chu S, Peng R, Liu M, Chen Z, Jin B, Chu S. Synthesis, microstructure, growth mechanism and photoluminescence of high quality [0001]-oriented InN nanowires and nanonecklaces. CrystEngComm 2015. [DOI: 10.1039/c5ce00137d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel indium nitride (InN) nanowires and nanonecklaces were grown on a single substrate and characterised, and the growth mechanism and of the nanonecklaces was studied.
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Affiliation(s)
- Huiqiang Liu
- State Key Laboratory of Optoelectronic Materials and Technology
- Sun Yat-Sen University
- Guangdong Guangzhou 510275, China
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials
- Southwest University of Science and Technology
| | - Sheng Chu
- State Key Laboratory of Optoelectronic Materials and Technology
- Sun Yat-Sen University
- Guangdong Guangzhou 510275, China
| | - Rufang Peng
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials
- Southwest University of Science and Technology
- Sichuan Mianyang 621010, China
| | - Min Liu
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials
- Southwest University of Science and Technology
- Sichuan Mianyang 621010, China
| | - Zuxin Chen
- State Key Laboratory of Optoelectronic Materials and Technology
- Sun Yat-Sen University
- Guangdong Guangzhou 510275, China
| | - Bo Jin
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials
- Southwest University of Science and Technology
- Sichuan Mianyang 621010, China
| | - Shijin Chu
- State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials
- Southwest University of Science and Technology
- Sichuan Mianyang 621010, China
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15
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Petersen G, Hoffmann EA, Schuh D, Wegscheider W, Giedke G, Ludwig S. Large nuclear spin polarization in gate-defined quantum dots using a single-domain nanomagnet. PHYSICAL REVIEW LETTERS 2013; 110:177602. [PMID: 23679779 DOI: 10.1103/physrevlett.110.177602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 03/13/2013] [Indexed: 06/02/2023]
Abstract
The electron-nuclei (hyperfine) interaction is central to spin qubits in solid state systems. It can be a severe decoherence source but also allows dynamic access to the nuclear spin states. We study a double quantum dot exposed to an on-chip single-domain nanomagnet and show that its inhomogeneous magnetic field crucially modifies the complex nuclear spin dynamics such that the Overhauser field tends to compensate external magnetic fields. This turns out to be beneficial for polarizing the nuclear spin ensemble. We reach a nuclear spin polarization of ≃50%, unrivaled in lateral dots, and explain our manipulation technique using a comprehensive rate equation model.
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Affiliation(s)
- Gunnar Petersen
- Center for Nanoscience and Fakultät für Physik, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
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Zhang S, Dayeh SA, Li Y, Crooker SA, Smith DL, Picraux ST. Electrical spin injection and detection in silicon nanowires through oxide tunnel barriers. NANO LETTERS 2013; 13:430-435. [PMID: 23324028 DOI: 10.1021/nl303667v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We demonstrate all-electrical spin injection, transport, and detection in heavily n-type-doped Si nanowires using ferromagnetic Co/Al(2)O(3) tunnel barrier contacts. Analysis of both local and nonlocal spin valve signals at 4 K on the same nanowire device using a standard spin-transport model suggests that high spin injection efficiency (up to ~30%) and long spin diffusion lengths (up to ~6 μm) are achieved. These values exceed those reported for spin transport devices based on comparably doped bulk Si. The spin valve signals are found to be strongly bias and temperature dependent and can invert sign with changes in the dc bias current. The influence of the nanowire morphology on field-dependent switching of the contacts is also discussed. Owing to their nanoscale geometry, ~5 orders of magnitude less current is required to achieve nonlocal spin valve voltages comparable to those attained in planar microscale spin transport devices, suggesting lower power consumption and the potential for applications of Si nanowires in nanospintronics.
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Affiliation(s)
- Shixiong Zhang
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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