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Chaudhary P, Lu H, Lipatov A, Ahmadi Z, McConville JPV, Sokolov A, Shield JE, Sinitskii A, Gregg JM, Gruverman A. Low-Voltage Domain-Wall LiNbO 3 Memristors. Nano Lett 2020; 20:5873-5878. [PMID: 32574058 DOI: 10.1021/acs.nanolett.0c01836] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Application of conducting ferroelectric domain walls (DWs) as functional elements may facilitate development of conceptually new resistive switching devices. In a conventional approach, several orders of magnitude change in resistance can be achieved by controlling the DW density using supercoercive voltage. However, a deleterious characteristic of this approach is high-energy cost of polarization reversal due to high leakage current. Here, we demonstrate a new approach based on tuning the conductivity of DWs themselves rather than on domain rearrangement. Using LiNbO3 capacitors with graphene, we show that resistance of a device set to a polydomain state can be continuously tuned by application of subcoercive voltage. The tuning mechanism is based on the reversible transition between the conducting and insulating states of DWs. The developed approach allows an energy-efficient control of resistance without the need for domain structure modification. The developed memristive devices are promising for multilevel memories and neuromorphic computing applications.
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Affiliation(s)
- P Chaudhary
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - H Lu
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - A Lipatov
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - Z Ahmadi
- Department of Mechanical & Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - J P V McConville
- Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, U.K
| | - A Sokolov
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - J E Shield
- Department of Mechanical & Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - A Sinitskii
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588, United States
| | - J M Gregg
- Centre for Nanostructured Media, School of Mathematics and Physics, Queen's University Belfast, Belfast BT7 1NN, U.K
| | - A Gruverman
- Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, United States
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Rajapitamahuni A, Zhang L, Koten MA, Singh VR, Burton JD, Tsymbal EY, Shield JE, Hong X. Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation. Phys Rev Lett 2016; 116:187201. [PMID: 27203341 DOI: 10.1103/physrevlett.116.187201] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 06/05/2023]
Abstract
The relatively low magnetocrystalline anisotropy (MCA) in strongly correlated manganites (La,Sr)MnO_{3} has been a major hurdle for implementing them in spintronic applications. Here we report an unusual, giant enhancement of in-plane MCA in 6 nm La_{0.67}Sr_{0.33}MnO_{3} (LSMO) films grown on (001) SrTiO_{3} substrates when the top 2 nm is patterned into periodic stripes of 100 or 200 nm width. Planar Hall effect measurements reveal an emergent uniaxial anisotropy superimposed on one of the original biaxial easy axes for unpatterned LSMO along ⟨110⟩ directions, with a 50-fold enhanced anisotropy energy density of 5.6×10^{6} erg/cm^{3} within the nanostripes, comparable to the value for cobalt. The magnitude and direction of the uniaxial anisotropy exclude shape anisotropy and the step edge effect as its origin. High resolution transmission electron microscopy studies reveal a nonequilibrium strain distribution and drastic suppression in the c-axis lattice constant within the nanostructures, which is the driving mechanism for the enhanced uniaxial MCA, as suggested by first-principles density functional calculations.
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Affiliation(s)
- A Rajapitamahuni
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - L Zhang
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - M A Koten
- Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - V R Singh
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - J D Burton
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - E Y Tsymbal
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - J E Shield
- Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
| | - X Hong
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0299, USA
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Abstract
STEM images and elemental maps of Mn and Bi showing formation of complex core–shell and three-layer structure.
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Affiliation(s)
- P. Mukherjee
- Physics & Astronomy
- University of Nebraska
- Lincoln
- USA
- Nebraska Center for Materials and Nanoscience
| | - B. Balamurugan
- Physics & Astronomy
- University of Nebraska
- Lincoln
- USA
- Nebraska Center for Materials and Nanoscience
| | - J. E. Shield
- Nebraska Center for Materials and Nanoscience
- University of Nebraska
- Lincoln
- USA
- Mechanical & Materials Engineering
| | - D. J. Sellmyer
- Physics & Astronomy
- University of Nebraska
- Lincoln
- USA
- Nebraska Center for Materials and Nanoscience
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Yu Y, Mukherjee P, Tian Y, Li XZ, Shield JE, Sellmyer DJ. Direct chemical synthesis of L1(0)-FePtAu nanoparticles with high coercivity. Nanoscale 2014; 6:12050-12055. [PMID: 25189100 DOI: 10.1039/c4nr02345e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report a facile synthesis of hard magnetic L10-FePtAu nanoparticles by coreduction of Fe(acac)3, Pt(acac)2 (acac = acetylacetonate) and gold acetate in oleylamine. In the current reaction condition, NP sizes are controlled to be 5.5 to 11.0 nm by changing the amount of Au doping. When the Au composition in the NPs is higher than 14%, the hard magnetic NPs are directly obtained without any annealing. The highest coercivity of 12.15 kOe at room temperature could be achieved for the NPs with 32% Au doping, which is much higher than the coercivities reported by the previous studies on solution-synthesized FePt nanoparticles. The reported one-pot synthesis of L10-FePtAu NPs may help to build superstrong magnets for magnetic or data-storage applications.
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Affiliation(s)
- Yongsheng Yu
- Nebraska Center for Materials and Nanoscience & Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
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Kumar P, Kashyap A, Balamurugan B, Shield JE, Sellmyer DJ, Skomski R. Permanent magnetism of intermetallic compounds between light and heavy transition-metal elements. J Phys Condens Matter 2014; 26:064209. [PMID: 24469225 DOI: 10.1088/0953-8984/26/6/064209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
First-principle calculations are used to investigate the intrinsic magnetic properties of intermetallic alloys of the type XMn, where X is a 4d or 5d element and M is Fe or Co. Emphasis is on the hexagonal C14 Laves-phase 1:2 and 1:5 alloys, the latter crystallizing in the CaCu5 structure. These series are of interest in permanent magnetism from fundamental and practical viewpoints, respectively. In the former, the unit cells form a prototypical motif where a heavy atom with high spin-orbit coupling and magnetocrystalline anisotropy is surrounded by many somewhat smaller M atoms with high magnetization, and the latter are Laves-phase derivatives of renewed interest in permanent magnetism. Our DFT calculations predict magnetic moments, magnetizations and anisotropies, as well as formation energies. The results are analyzed across the 4d and 5d series, especially with respect to hybridization effects between 3d and 4d/5d bands.
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Yu Y, Sun K, Tian Y, Li XZ, Kramer MJ, Sellmyer DJ, Shield JE, Sun S. One-pot synthesis of urchin-like FePd-Fe3O4 and their conversion into exchange-coupled L1(0)-FePd-Fe nanocomposite magnets. Nano Lett 2013; 13:4975-9. [PMID: 24041265 DOI: 10.1021/nl403043d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report a one-pot synthesis of urchin-like FePd-Fe3O4 nanocomposites, spherical clusters of FePd nanoparticles (NPs) with spikes of Fe3O4 nanorods (NRs), via controlled thermal decomposition of Fe(CO)5 and reduction of Pd(acac)2. The FePd NPs with sizes between 6 and 9 nm self-aggregate into 60 nm superparticles (SPs), and Fe3O4 NRs grow on the surface of these SPs. Reductive annealing at 500 °C converts the FePd-Fe3O4 into exchange-coupled nanocomposites L1(0)-FePd-Fe with their Hc tunable from 0.8 to 2.6 kOe and Ms controlled from 90 to 190 emu/g. The work provides a general approach to L1(0)-FePd-Fe nanocomposite magnets for understanding exchange coupling at the nanoscale. The concept may be extended to other magnetic nanocomposite systems and may help to build superstrong magnets for magnetic applications.
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Affiliation(s)
- Yongsheng Yu
- Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States
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Shastri A, Borsa F, Torgeson DR, Shield JE, Goldman AI. NMR and NQR study of the electronic and structural properties of Al-Cu-Fe and Al-Cu-Ru quasicrystals. Phys Rev B Condens Matter 1994; 50:15651-15667. [PMID: 9975931 DOI: 10.1103/physrevb.50.15651] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Shield JE, Hoppe C, McCallum RW, Goldman AI, Kelton KF, Gibbons PC. Icosahedral phase stabilities in Al-Cu-Ru alloys. Phys Rev B Condens Matter 1992; 45:2063-2072. [PMID: 10001720 DOI: 10.1103/physrevb.45.2063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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