1
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Wong HF, Ng SM, Zhang W, Liu YK, Wong PKJ, Tang CS, Lam KK, Zhao XW, Meng ZG, Fei LF, Cheng WF, Nordheim DV, Wong WY, Wang ZR, Ploss B, Dai JY, Mak CL, Wee ATS, Leung CW. Modulating Magnetism in Ferroelectric Polymer-Gated Perovskite Manganite Films with Moderate Gate Pulse Chains. ACS APPLIED MATERIALS & INTERFACES 2020; 12:56541-56548. [PMID: 33283518 DOI: 10.1021/acsami.0c14172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Most previous attempts on achieving electric-field manipulation of ferromagnetism in complex oxides, such as La0.66Sr0.33MnO3 (LSMO), are based on electrostatically induced charge carrier changes through high-k dielectrics or ferroelectrics. Here, the use of a ferroelectric copolymer, polyvinylidene fluoride with trifluoroethylene [P(VDF-TrFE)], as a gate dielectric to successfully modulate the ferromagnetism of the LSMO thin film in a field-effect device geometry is demonstrated. Specifically, through the application of low-voltage pulse chains inadequate to switch the electric dipoles of the copolymer, enhanced tunability of the oxide magnetic response is obtained, compared to that induced by ferroelectric polarization. Such observations have been attributed to electric field-induced oxygen vacancy accumulation/depletion in the LSMO layer upon the application of pulse chains, which is supported by surface-sensitive-characterization techniques, including X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism. These techniques not only unveil the electrochemical nature of the mechanism but also establish a direct correlation between the oxygen vacancies created and subsequent changes to the valence states of Mn ions in LSMO. These demonstrations based on the pulsing strategy can be a viable route equally applicable to other functional oxides for the construction of electric field-controlled magnetic devices.
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Affiliation(s)
- Hon Fai Wong
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Sheung Mei Ng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wen Zhang
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Yu Kuai Liu
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Ping Kwan Johnny Wong
- School of Electronics and Information and School of Microelectronics, Northwestern Polytechnical University, 127 West Youyi Road, Xi'an, Shaanxi 710072, China
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Sin Tang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Ka Kin Lam
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Xu Wen Zhao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zhen Gong Meng
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lin Feng Fei
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Wang Fai Cheng
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Danny von Nordheim
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Wai Yeung Wong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Zong Rong Wang
- State Key Lab of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Bernd Ploss
- Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07743 Jena, Germany
| | - Ji-Yan Dai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Chee Leung Mak
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Chi Wah Leung
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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2
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Molinari A, Hahn H, Kruk R. Voltage-Control of Magnetism in All-Solid-State and Solid/Liquid Magnetoelectric Composites. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1806662. [PMID: 30785649 DOI: 10.1002/adma.201806662] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 12/20/2018] [Indexed: 06/09/2023]
Abstract
The control of magnetism by means of low-power electric fields, rather than dissipative flowing currents, has the potential to revolutionize conventional methods of data storage and processing, sensing, and actuation. A promising strategy relies on the utilization of magnetoelectric composites to finely tune the interplay between electric and magnetic degrees of freedom at the interface of two functional materials. Albeit early works predominantly focused on the magnetoelectric coupling at solid/solid interfaces; however, recently there has been an increased interest related to the opportunities offered by liquid-gating techniques. Here, a comparative overview on voltage control of magnetism in all-solid-state and solid/liquid composites is presented within the context of the principal coupling mediators, i.e., strain, charge carrier doping, and ionic intercalation. Further, an exhaustive and critical discussion is carried out, concerning the suitability of using the common definition of coupling coefficient α C = Δ M Δ E to compare the strength of the interaction between electricity and magnetism among different magnetoelectric systems.
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Affiliation(s)
- Alan Molinari
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Horst Hahn
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
- KIT-TUD-Joint Research Laboratory Nanomaterials, Technical University Darmstadt, Jovanka-Bontschits-Strasse 2, 64287, Darmstadt, Germany
| | - Robert Kruk
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
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3
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Wang X, Wang H, Ma J, Zhao X, Zhao J. Efficiently Rotating the Magnetization Vector in a Magnetic Semiconductor via Organic Molecules. ACS APPLIED MATERIALS & INTERFACES 2019; 11:6615-6623. [PMID: 30652468 DOI: 10.1021/acsami.8b19529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Local manipulation of the magnetization direction is of significant importance in spintronics because it provides an effective way in nonvolatile device applications for ultrahigh density information storage. However, this modulation is usually restricted to a limited range even through large power input. We demonstrate a large rotation of the magnetization vector in a magnetic semiconductor (Ga,Mn)As (110) thin film by surface decoration of self-assembled molecules. The carrier density of the film is vastly changed by two kinds of molecules acting as electron donors and acceptors, resulting in a prominent variation of the Curie temperature and magnetic anisotropy. The magnetic anisotropic fields tuned by the molecules could be quantitatively determined by planar Hall measurements, based on which the largest rotation angle is calculated to be ∼27°. This value doubles the result obtained by the electric field up to 0.4 V/nm, which is approaching the breakdown strength of common dielectrics. Our work offers a new functionality for effectively tuning the magnetization direction of nanoscale bits, without relying on the magnetic field, spin current, or mechanical strain.
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Affiliation(s)
- Xiaolei Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Jialin Ma
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Xupeng Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors , Chinese Academy of Sciences , P.O. Box 912, Beijing 100083 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100190 , China
- CAS Center for Excellence in Topological Quantum Computation , University of Chinese Academy of Sciences , Beijing 100190 , China
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4
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Kalachyova Y, Guselnikova O, Postnikov P, Fitl P, Lapcak L, Svorcik V, Lyutakov O. Reversible switching of PEDOT:PSS conductivity in the dielectric–conductive range through the redistribution of light-governing polymers. RSC Adv 2018; 8:11198-11206. [PMID: 35541520 PMCID: PMC9078990 DOI: 10.1039/c7ra12624g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 03/06/2018] [Indexed: 12/22/2022] Open
Abstract
One of the biggest challenges in the field of organic electronics is the creation of flexible, stretchable, and biofavorable materials. Here the simple and repeatable method for reversible writing/erasing of arbitrary conductive pattern in conductive polymer thin film is proposed. The copolymer azo-modified poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) was synthesized to achieve reversible photo-induced local electrical switching in the insulator–semimetal range. The photoisomerization of the polymer was induced by grafting nitrobenzenediazonium tosylate to the PSS main chains. While the as-deposited PEDOT:PSS thin films showed good conductivity, the modification procedure generated polymer redistribution, resulting in an island-like PEDOT distribution and the loss of conductivity. Further local illumination (430 nm) led to the azo-isomerization redistribution of the polymer chains and the creation of a conductive pattern in the insulating polymer film. The created pattern could then be erased by illumination at a second wavelength (470 nm), which was attributed to induction of reverse azo-isomerization. In this way, the reversible writing/erasing of arbitrary conductive patterns in thin polymer films was realized. Chemical modification of PEDOT:PSS allows grafting light-switchable moieties to PSS chains and light induced reversible tuning of materials conductivity in dielectric-semimetal range.![]()
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Affiliation(s)
- Y. Kalachyova
- Department of Solid State Engineering
- University of Chemistry and Technology
- Prague 16628
- Czech Republic
- Department of Technology of Organic Substances and Polymer Materials
| | - O. Guselnikova
- Department of Solid State Engineering
- University of Chemistry and Technology
- Prague 16628
- Czech Republic
- Department of Technology of Organic Substances and Polymer Materials
| | - P. Postnikov
- Department of Technology of Organic Substances and Polymer Materials
- Tomsk Polytechnic University
- Tomsk 634050
- Russia
| | - P. Fitl
- Department of Physics and Measurements
- University of Chemistry and Technology
- Prague 16628
- Czech Republic
| | - L. Lapcak
- Central Laboratories
- University of Chemistry and Technology
- Prague
- Czech Republic
| | - V. Svorcik
- Department of Solid State Engineering
- University of Chemistry and Technology
- Prague 16628
- Czech Republic
| | - O. Lyutakov
- Department of Solid State Engineering
- University of Chemistry and Technology
- Prague 16628
- Czech Republic
- Department of Technology of Organic Substances and Polymer Materials
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5
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Vopson MM, Fetisov YK, Caruntu G, Srinivasan G. Measurement Techniques of the Magneto-Electric Coupling in Multiferroics. MATERIALS 2017; 10:ma10080963. [PMID: 28817089 PMCID: PMC5578329 DOI: 10.3390/ma10080963] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 08/07/2017] [Accepted: 08/09/2017] [Indexed: 11/16/2022]
Abstract
The current surge of interest in multiferroic materials demands specialized measurement techniques to support multiferroics research. In this review article we detail well-established measurement techniques of the magneto-electric coupling coefficient in multiferroic materials, together with newly proposed ones. This work is intended to serve as a reference document for anyone willing to develop experimental measurement techniques of multiferroic materials.
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Affiliation(s)
- M M Vopson
- School of Earth and Environmental Sciences, Faculty of Science, University of Portsmouth, Portsmouth PO1 3QL, UK.
| | - Y K Fetisov
- Moscow Technological University, MIREA, Moscow 119454, Russia.
| | - G Caruntu
- Department of Chemistry and Biochemistry, Central Michigan University, 1200 S. Franklin St., Mount Pleasant, MI 48858, USA.
| | - G Srinivasan
- Physics Department, Oakland University, Rochester, MI 48309-4401, USA.
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6
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Taniyama T. Electric-field control of magnetism via strain transfer across ferromagnetic/ferroelectric interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:504001. [PMID: 26613163 DOI: 10.1088/0953-8984/27/50/504001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
By taking advantage of the coupling between magnetism and ferroelectricity, ferromagnetic (FM)/ferroelectric (FE) multiferroic interfaces play a pivotal role in manipulating magnetism by electric fields. Integrating the multiferroic heterostructures into spintronic devices significantly reduces energy dissipation from Joule heating because only an electric field is required to switch the magnetic element. New concepts of storage and processing of information thus can be envisioned when the electric-field control of magnetism is a viable alternative to the traditional current based means of controlling magnetism. This article reviews some salient aspects of the electric-field effects on magnetism, providing a short overview of the mechanisms of magneto-electric (ME) coupling at the FM/FE interfaces. A particular emphasis is placed on the ME effect via interfacial magneto-elastic coupling arising from strain transfer from the FE to FM layer. Recent results that demonstrate the electric-field control of magnetic anisotropy, magnetic order, magnetic domain wall motion, and etc are described. Obstacles that need to be overcome are also discussed for making this a reality for future device applications.
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Affiliation(s)
- Tomoyasu Taniyama
- Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503, Japan
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7
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Wang X, Wang H, Pan D, Keiper T, Li L, Yu X, Lu J, Lochner E, von Molnár S, Xiong P, Zhao J. Robust Manipulation of Magnetism in Dilute Magnetic Semiconductor (Ga,Mn)As by Organic Molecules. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:8043-8050. [PMID: 26540329 DOI: 10.1002/adma.201503547] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/21/2015] [Indexed: 06/05/2023]
Abstract
Surface adsorption of organic molecules provides a new method for the robust manipulation of ferromagnetism in (Ga,Mn)As. Electron acceptor and donor molecules yield significant enhancement and suppression, respectively, of ferromagnetism with modulation of the Curie temperature spanning 36 K. Dip-pen nanolithography is employed to directly pattern monolayers on (Ga,Mn)As, which is presented as a novel pathway toward producing magnetic nanostructures.
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Affiliation(s)
- Xiaolei Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Dong Pan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Timothy Keiper
- Department of Physics, Florida State University, Tallahassee, FL, 32306, USA
| | - Lixia Li
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Xuezhe Yu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Jun Lu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
| | - Eric Lochner
- Department of Physics, Florida State University, Tallahassee, FL, 32306, USA
| | - Stephan von Molnár
- Department of Physics, Florida State University, Tallahassee, FL, 32306, USA
| | - Peng Xiong
- Department of Physics, Florida State University, Tallahassee, FL, 32306, USA
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing, 100083, China
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8
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In-plane tunnelling field-effect transistor integrated on Silicon. Sci Rep 2015; 5:14367. [PMID: 26403693 PMCID: PMC4585907 DOI: 10.1038/srep14367] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 08/13/2015] [Indexed: 11/29/2022] Open
Abstract
Silicon has persevered as the primary substrate of microelectronics during last decades. During last years, it has been gradually embracing the integration of ferroelectricity and ferromagnetism. The successful incorporation of these two functionalities to silicon has delivered the desired non-volatility via charge-effects and giant magneto-resistance. On the other hand, there has been a numerous demonstrations of the so-called magnetoelectric effect (coupling between ferroelectric and ferromagnetic order) using nearly-perfect heterostructures. However, the scrutiny of the ingredients that lead to magnetoelectric coupling, namely magnetic moment and a conducting channel, does not necessarily require structural perfection. In this work, we circumvent the stringent requirements for epilayers while preserving the magnetoelectric functionality in a silicon-integrated device. Additionally, we have identified an in-plane tunnelling mechanism which responds to a vertical electric field. This genuine electroresistance effect is distinct from known resistive-switching or tunnel electro resistance.
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9
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Affiliation(s)
- Arvin Kakekhani
- Department of Physics, ‡Department of Applied Physics, §Department of Mechanical Engineering and Materials Science, ⊥Center for Research on Interface Structure and Phenomena (CRISP), Yale University, New Haven, Connecticut 06520, United States
| | - Sohrab Ismail-Beigi
- Department of Physics, ‡Department of Applied Physics, §Department of Mechanical Engineering and Materials Science, ⊥Center for Research on Interface Structure and Phenomena (CRISP), Yale University, New Haven, Connecticut 06520, United States
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10
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Lupascu DC, Wende H, Etier M, Nazrabi A, Anusca I, Trivedi H, Shvartsman VV, Landers J, Salamon S, Schmitz-Antoniak C. Measuring the magnetoelectric effect across scales. ACTA ACUST UNITED AC 2015. [DOI: 10.1002/gamm.201510003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Siušys A, Sadowski J, Sawicki M, Kret S, Wojciechowski T, Gas K, Szuszkiewicz W, Kaminska A, Story T. All-wurtzite (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy. NANO LETTERS 2014; 14:4263-4272. [PMID: 24971488 DOI: 10.1021/nl500896d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold catalyst have been investigated. (In,Ga)As core nanowires were grown at high temperature (500 °C) whereas (Ga,Mn)As shells were deposited on the {11̅00} side facets of the cores at much lower temperature (220 °C). High-resolution transmission electron microscopy images and high spectral resolution Raman scattering data show that both the cores and the shells of the nanowires have wurtzite crystalline structure. Scanning and transmission electron microscopy observations show smooth (Ga,Mn)As shells containing 5% of Mn epitaxially deposited on (In,Ga)As cores containing about 10% of In without any misfit dislocations at the core-shell interface. With the In content in the (In,Ga)As cores larger than 5% the (In,Ga)As lattice parameter is higher than that of (Ga,Mn)As and the shell is in the tensile strain state. Elaborated magnetic studies indicate the presence of ferromagnetic coupling in (Ga,Mn)As shells at the temperatures in excess of 33 K. This coupling is maintained only in separated mesoscopic volumes resulting in an overall superparamagnetic behavior which gets blocked below ∼ 17 K.
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Affiliation(s)
- Aloyzas Siušys
- Institute of Physics, Polish Academy of Sciences , al. Lotników 32/46, PL 02-668 Warszawa, Poland
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12
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Hu L, Dalgleish S, Matsushita MM, Yoshikawa H, Awaga K. Storage of an electric field for photocurrent generation in ferroelectric-functionalized organic devices. Nat Commun 2014; 5:3279. [DOI: 10.1038/ncomms4279] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 01/19/2014] [Indexed: 11/09/2022] Open
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13
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Barnes SE, Ieda J, Maekawa S. Rashba spin-orbit anisotropy and the electric field control of magnetism. Sci Rep 2014; 4:4105. [PMID: 24531151 PMCID: PMC3925965 DOI: 10.1038/srep04105] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 01/24/2014] [Indexed: 11/10/2022] Open
Abstract
The control of the magnetism of ultra-thin ferromagnetic layers using an electric field, rather than a current, has many potential technologically important applications. It is usually insisted that such control occurs via an electric field induced surface charge doping that modifies the magnetic anisotropy. However, it remains the case that a number of key experiments cannot be understood within such a scenario. Much studied is the spin-splitting of the conduction electrons of non-magnetic metals or semi-conductors due to the Rashba spin-orbit coupling. This reflects a large surface electric field. For a magnet, this same splitting is modified by the exchange field resulting in a large magnetic anisotropy energy via the Dzyaloshinskii-Moriya mechanism. This different, yet traditional, path to an electrically induced anisotropy energy can explain the electric field, thickness, and material dependence reported in many experiments.
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Affiliation(s)
- Stewart E Barnes
- 1] Physics Department, University of Miami, Coral Gables, FL 33124, USA [2] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Jun'ichi Ieda
- 1] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan [2] CREST, Japan Science and Technology Agency, Sanbancho, Tokyo 102-0075, Japan
| | - Sadamichi Maekawa
- 1] Advanced Science Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan [2] CREST, Japan Science and Technology Agency, Sanbancho, Tokyo 102-0075, Japan
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14
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Orientation of lamellar crystals and its correlation with switching behavior in ferroelectric P(VDF-TrFE) ultra-thin films. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Przybylińska H, Springholz G, Lechner RT, Hassan M, Wegscheider M, Jantsch W, Bauer G. Magnetic-field-induced ferroelectric polarization reversal in the multiferroic Ge(1-x)Mn(x)Te semiconductor. PHYSICAL REVIEW LETTERS 2014; 112:047202. [PMID: 24580486 DOI: 10.1103/physrevlett.112.047202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 11/14/2013] [Indexed: 06/03/2023]
Abstract
Ge(1-x)Mn(x)Te is shown to be a multiferroic semiconductor, exhibiting both ferromagnetic and ferroelectric properties. By ferromagnetic resonance we demonstrate that both types of order are coupled to each other. As a result, magnetic-field-induced ferroelectric polarization reversal is achieved. Switching of the spontaneous electric dipole moment is monitored by changes in the magnetocrystalline anisotropy. This also reveals that the ferroelectric polarization reversal is accompanied by a reorientation of the hard and easy magnetization axes. By tuning the GeMnTe composition, the interplay between ferromagnetism and ferroelectricity can be controlled.
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Affiliation(s)
- H Przybylińska
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - G Springholz
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - R T Lechner
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria and Institut für Physik, Montanuniversität Leoben, A-8700 Leoben, Austria
| | - M Hassan
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria and Department of Physics, University of the Punjab, Lahore-54590, Pakistan
| | - M Wegscheider
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - W Jantsch
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - G Bauer
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
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16
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Wu Y, Gu Q, Ding G, Tong F, Hu Z, Jonas AM. Confinement Induced Preferential Orientation of Crystals and Enhancement of Properties in Ferroelectric Polymer Nanowires. ACS Macro Lett 2013; 2:535-538. [PMID: 35581813 DOI: 10.1021/mz400208k] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The physical properties of polymers strongly depend on the molecular or supermolecular order and orientation. Here we demonstrate the preferential orientation of lamellar crystals and the enhancement of ferro/piezoelectric properties in individual poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) nanowires fabricated from anodic alumina oxide (AAO) templates. The crystallographic a axis of P(VDF-TrFE) was found to be aligned along the long axis of nanowires due to geometrical confinement and grapho-expitaxial crystals growth. The alignment of lamellar crystals in P(VDF-TrFE) nanowires and enhancement of crystallization translated into improved ferro/piezoelectric properties such as lower coercive field and higher piezoelectric coefficient, testified by piezoresponse force microscopy images and piezoresponse hysteresis loops.
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Affiliation(s)
- Yangjiang Wu
- Center
for Soft
Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - Qingzhao Gu
- Center
for Soft
Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - Guangzhu Ding
- Center
for Soft
Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - Fuqiang Tong
- Department of Physics and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006, China
| | - Zhijun Hu
- Center
for Soft
Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China
| | - Alain M. Jonas
- Institue of Condensed
Matter and Nanosciences − Bio and Soft Matter (IMCN/BSMA), Université Catholique de Louvain, Croix du Sud 1/L7.04.02, 1348 Louvain-la-Neuve, Belgium
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17
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Subramanian H, Han JE. In-plane uniaxial magnetic anisotropy in (Ga, Mn)As due to local lattice distortions around Mn²⁺ ions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:206005. [PMID: 23615156 DOI: 10.1088/0953-8984/25/20/206005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We theoretically investigate the interplay between local lattice distortions around the Mn(2+) impurity ion and its magnetization, mediated through spin-orbit coupling of holes. We show that the tetrahedral symmetry around the Mn(2+) ion is spontaneously broken and that local Jahn-Teller distortions coupled with growth strain result in uniaxial magnetic anisotropy. We also account for the experimentally observed in-plane uniaxial magnetic anisotropy rotation due to variation of hole density. According to this model, lack of inversion and top-down symmetries of (Ga, Mn)As layers lead to in-plane biaxial symmetry breaking in the presence of Jahn-Teller distortions.
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18
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Vaz CAF. Electric field control of magnetism in multiferroic heterostructures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:333201. [PMID: 22824827 DOI: 10.1088/0953-8984/24/33/333201] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We review the recent developments in the electric field control of magnetism in multiferroic heterostructures, which consist of heterogeneous materials systems where a magnetoelectric coupling is engineered between magnetic and ferroelectric components. The magnetoelectric coupling in these composite systems is interfacial in origin, and can arise from elastic strain, charge, and exchange bias interactions, with different characteristic responses and functionalities. Moreover, charge transport phenomena in multiferroic heterostructures, where both magnetic and ferroelectric order parameters are used to control charge transport, suggest new possibilities to control the conduction paths of the electron spin, with potential for device applications.
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Affiliation(s)
- C A F Vaz
- SwissFEL, Paul Scherrer Institut, Villigen PSI, Switzerland.
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19
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Chen G, Song C, Chen C, Gao S, Zeng F, Pan F. Resistive switching and magnetic modulation in cobalt-doped ZnO. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:3515-20. [PMID: 22678882 DOI: 10.1002/adma.201201595] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Revised: 05/21/2012] [Indexed: 05/10/2023]
Abstract
A combination of resistive switching and magnetic modulation gives rise to the integration of room temperature ferromagnetism (spin) and electrical properties (charge) into a simple Pt/Co:ZnO/Pt structure due to the formation of oxygen vacancy-based conductive filaments. This is promising for broadening the applications of random access memories to encode quaternary information.
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Affiliation(s)
- Guang Chen
- Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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20
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Stolichnov I, Maksymovych P, Mikheev E, Kalinin SV, Tagantsev AK, Setter N. Cold-field switching in PVDF-TrFE ferroelectric polymer nanomesas. PHYSICAL REVIEW LETTERS 2012; 108:027603. [PMID: 22324709 DOI: 10.1103/physrevlett.108.027603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Indexed: 05/31/2023]
Abstract
Polarization reversal in ferroelectric nanomesas of polyvinylidene fluoride with trifluoroethylene has been probed by ultrahigh vacuum piezoresponse force microscopy in a wide temperature range from 89 to 326 K. In dramatic contrast to the macroscopic data, the piezoresponse force microscopy local switching was nonthermally activated and, at the same time, occurring at electric fields significantly lower than the intrinsic switching threshold. A "cold-field" defect-mediated extrinsic switching is shown to be an adequate scenario describing this peculiar switching behavior. The extrinsic character of the observed polarization reversal suggests that there is no fundamental bar for lowering the coercive field in ferroelectric polymer nanostructures, which is of importance for their applications in functional electronics.
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Affiliation(s)
- Igor Stolichnov
- Ceramics Laboratory, EPFL-Swiss Federal Institute of Technology, Lausanne 1015, Switzerland.
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21
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Guo D, Stolichnov I, Setter N. Thermally Induced Cooperative Molecular Reorientation and Nanoscale Polarization Switching Behaviors of Ultrathin Poly(vinylidene fluoride-trifluoroethylene) Films. J Phys Chem B 2011; 115:13455-66. [DOI: 10.1021/jp2061442] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dong Guo
- Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China
| | - Igor Stolichnov
- Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
| | - Nava Setter
- Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne, Switzerland
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22
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Suzuki Y, Kubota H, Tulapurkar A, Nozaki T. Spin control by application of electric current and voltage in FeCo-MgO junctions. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3658-3678. [PMID: 21859728 DOI: 10.1098/rsta.2011.0190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Efficient control and detection of spins are the most important tasks in spintronics. The current and voltage applied to a magnetic tunnel junction may exert a torque on the magnetic thin layer in the junction and cause its reversal or continuous precession. The discovery of the giant tunnelling magnetoresistance effect in ferromagnetic tunnelling junctions using an MgO barrier enabled us to obtain a large signal output from the magnetization reversal and precession. Also, the interplay of large spin configuration-electric conduction coupling provides highly nonlinear effects like the spin-torque diode effect. The negative resistance effect and amplification using it are predicted. A new discovery about a voltage-induced magnetic anisotropy change in Fe ultrathin films is also discussed.
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Affiliation(s)
- Yoshishige Suzuki
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
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23
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Velev JP, Jaswal SS, Tsymbal EY. Multi-ferroic and magnetoelectric materials and interfaces. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3069-3097. [PMID: 21727115 DOI: 10.1098/rsta.2010.0344] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.
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Affiliation(s)
- J P Velev
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE 68588-0299, USA
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24
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Stolichnov I, Riester SWE, Mikheev E, Setter N, Rushforth AW, Edmonds KW, Campion RP, Foxon CT, Gallagher BL, Jungwirth T, Trodahl HJ. Ferroelectric polymer gates for non-volatile field effect control of ferromagnetism in (Ga, Mn)As layers. NANOTECHNOLOGY 2011; 22:254004. [PMID: 21572188 DOI: 10.1088/0957-4484/22/25/254004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
(Ga, Mn)As and other diluted magnetic semiconductors (DMS) attract a great deal of attention for potential spintronic applications because of the possibility of controlling the magnetic properties via electrical gating. Integration of a ferroelectric gate on the DMS channel adds to the system a non-volatile memory functionality and permits nanopatterning via the polarization domain engineering. This topical review is focused on the multiferroic system, where the ferromagnetism in the (Ga, Mn)As DMS channel is controlled by the non-volatile field effect of the spontaneous polarization. Use of ferroelectric polymer gates in such heterostructures offers a viable alternative to the traditional oxide ferroelectrics generally incompatible with DMS. Here we review the proof-of-concept experiments demonstrating the ferroelectric control of ferromagnetism, analyze the performance issues of the ferroelectric gates and discuss prospects for further development of the ferroelectric/DMS heterostructures toward the multiferroic field effect transistor.
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Affiliation(s)
- I Stolichnov
- Ceramics Laboratory, EPFL-Swiss Federal Institute of Technology, Lausanne, Switzerland
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25
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Hao J, Zhang Y, Wei X. Electric-Induced Enhancement and Modulation of Upconversion Photoluminescence in Epitaxial BaTiO3:Yb/Er Thin Films. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101374] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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26
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Hao J, Zhang Y, Wei X. Electric-Induced Enhancement and Modulation of Upconversion Photoluminescence in Epitaxial BaTiO3:Yb/Er Thin Films. Angew Chem Int Ed Engl 2011; 50:6876-80. [DOI: 10.1002/anie.201101374] [Citation(s) in RCA: 278] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 04/21/2011] [Indexed: 11/08/2022]
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27
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28
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Chiba D, Matsukura F, Ohno H. Electrically defined ferromagnetic nanodots. NANO LETTERS 2010; 10:4505-4508. [PMID: 20923162 DOI: 10.1021/nl102379h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
While ferromagnetic nanodots are being widely studied from fundamental as well as application points of views, so far all the dots have been physically defined; once made, one cannot change their dimension or size. We show that ferromagnetic nanodots can be electrically defined. To realize this, we utilize an electric field to modulate the in-plane distribution of carriers in a ferromagnetic semiconductor (Ga,Mn)As film with a meshed gate structure having a large number of nanoscaled windows.
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Affiliation(s)
- Daichi Chiba
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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29
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Horák L, Sobáň Z, Holý V. Study of Mn interstitials in (Ga, Mn)As using high-resolution x-ray diffraction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:296009. [PMID: 21399326 DOI: 10.1088/0953-8984/22/29/296009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present a method for the determination of the concentration of Mn ions in nonequivalent interstitial positions in the lattice of (Ga, Mn)As. The Mn ions occupy substitutional and/or interstitial positions in the GaAs lattice and the dependence of the structure factor on their concentration differs for various diffractions and for different positions in the lattice. We measured several diffractions including weak diffractions, which are very sensitive to the Mn content. All measured diffraction curves were simultaneously fitted to a theoretical model and the densities of Mn ions, in particular interstitial positions, were obtained. The method reported here allows us to determine the amount of interstitial Mn which, according to current understanding, affects the ferromagnetic properties including the Curie temperature in (Ga, Mn)As.
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Affiliation(s)
- L Horák
- Faculty of Mathematics and Physics, Department of Electronic Structures, Charles University, Prague, Czech Republic.
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30
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Vaz CAF, Hoffman J, Ahn CH, Ramesh R. Magnetoelectric coupling effects in multiferroic complex oxide composite structures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:2900-18. [PMID: 20414887 DOI: 10.1002/adma.200904326] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The study of magnetoelectric materials has recently received renewed interest, in large part stimulated by breakthroughs in the controlled growth of complex materials and by the search for novel materials with functionalities suitable for next generation electronic devices. In this Progress Report, we present an overview of recent developments in the field, with emphasis on magnetoelectric coupling effects in complex oxide multiferroic composite materials.
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Affiliation(s)
- Carlos A F Vaz
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA.
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31
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Siddiqui L, Zainuddin ANM, Datta S. Electrically driven magnetization of diluted magnetic semiconductors actuated by the Overhauser effect. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:216002. [PMID: 21393728 DOI: 10.1088/0953-8984/22/21/216002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It is well known that the Curie temperature, and hence the magnetization, in diluted magnetic semiconductors (DMS) like Ga(1-x)Mn(x)As can be controlled by changing the equilibrium density of holes in the material. Here, we propose that even with a constant hole density, large changes in the magnetization can be obtained with a relatively small imbalance in the quasi-Fermi levels for up-spin and down-spin electrons. We show, by coupling the mean field theory of diluted magnetic semiconductor ferromagnetism with master equations governing the Mn spin-dynamics, that a mere splitting of the up-spin and down-spin quasi-Fermi levels by 0.1 meV will produce the effect of an external magnetic field as large as 1 T as long as the alternative relaxation paths for Mn spins (i.e. spin-lattice relaxation) can be neglected. The physics is similar to the classic Overhauser effect, also called the dynamic nuclear polarization, with the Mn impurities playing the role of the nucleus. We propose that a lateral spin-valve structure in an anti-parallel configuration with a DMS as the channel can be used to demonstrate this effect, as quasi-Fermi level splitting of such magnitude, inside the channel of similar systems, has already been experimentally demonstrated to produce polarization of paramagnetic impurity spins.
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Affiliation(s)
- L Siddiqui
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA.
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32
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Naber RCG, Asadi K, Blom PWM, de Leeuw DM, de Boer B. Organic nonvolatile memory devices based on ferroelectricity. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:933-45. [PMID: 20217816 DOI: 10.1002/adma.200900759] [Citation(s) in RCA: 215] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A memory functionality is a prerequisite for many applications of electronic devices. Organic nonvolatile memory devices based on ferroelectricity are a promising approach toward the development of a low-cost memory technology. In this Review Article we discuss the latest developments in this area with a focus on three of the most important device concepts: ferroelectric capacitors, field-effect transistors, and diodes. Integration of these devices into larger memory arrays is also discussed.
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33
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Nakano M, Tsukazaki A, Ohtomo A, Ueno K, Akasaka S, Yuji H, Nakahara K, Fukumura T, Kawasaki M. Electric-field [corrected] control of two-dimensional electrons in polymer-gated-oxide semiconductor heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:876-879. [PMID: 20217809 DOI: 10.1002/adma.200902162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Masaki Nakano
- Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan
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34
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Garcia V, Bibes M, Bocher L, Valencia S, Kronast F, Crassous A, Moya X, Enouz-Vedrenne S, Gloter A, Imhoff D, Deranlot C, Mathur ND, Fusil S, Bouzehouane K, Barthelemy A. Ferroelectric Control of Spin Polarization. Science 2010; 327:1106-10. [DOI: 10.1126/science.1184028] [Citation(s) in RCA: 584] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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35
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Maruyama T, Shiota Y, Nozaki T, Ohta K, Toda N, Mizuguchi M, Tulapurkar AA, Shinjo T, Shiraishi M, Mizukami S, Ando Y, Suzuki Y. Large voltage-induced magnetic anisotropy change in a few atomic layers of iron. NATURE NANOTECHNOLOGY 2009; 4:158-161. [PMID: 19265844 DOI: 10.1038/nnano.2008.406] [Citation(s) in RCA: 256] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 12/09/2008] [Indexed: 05/27/2023]
Abstract
In the field of spintronics, researchers have manipulated magnetization using spin-polarized currents. Another option is to use a voltage-induced symmetry change in a ferromagnetic material to cause changes in magnetization or in magnetic anisotropy. However, a significant improvement in efficiency is needed before this approach can be used in memory devices with ultralow power consumption. Here, we show that a relatively small electric field (less than 100 mV nm(-1)) can cause a large change (approximately 40%) in the magnetic anisotropy of a bcc Fe(001)/MgO(001) junction. The effect is tentatively attributed to the change in the relative occupation of 3d orbitals of Fe atoms adjacent to the MgO barrier. Simulations confirm that voltage-controlled magnetization switching in magnetic tunnel junctions is possible using the anisotropy change demonstrated here, which could be of use in the development of low-power logic devices and non-volatile memory cells.
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Affiliation(s)
- T Maruyama
- Graduate School of Engineering Science, Osaka University, Toyonaka, Japan
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36
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Novák V, Olejník K, Wunderlich J, Cukr M, Výborný K, Rushforth AW, Edmonds KW, Campion RP, Gallagher BL, Sinova J, Jungwirth T. Curie point singularity in the temperature derivative of resistivity in (Ga,Mn)As. PHYSICAL REVIEW LETTERS 2008; 101:077201. [PMID: 18764572 DOI: 10.1103/physrevlett.101.077201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 06/26/2008] [Indexed: 05/26/2023]
Abstract
We observe a singularity in the temperature derivative drho/dT of resistivity at the Curie point of high-quality (Ga,Mn)As ferromagnetic semiconductors with Tc's ranging from approximately 80 to 185 K. The character of the anomaly is sharply distinct from the critical contribution to transport in conventional dense-moment magnetic semiconductors and is reminiscent of the drho/dT singularity in transition metal ferromagnets. Within the critical region accessible in our experiments, the temperature dependence on the ferromagnetic side can be explained by dominant scattering from uncorrelated spin fluctuations. The singular behavior of drho/dT on the paramagnetic side points to the important role of short-range correlated spin fluctuations.
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Affiliation(s)
- V Novák
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
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