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Aldulaimi WAS, Okatan MB, Sendur K, Onbasli MC, Misirlioglu IB. Size driven barrier to chirality reversal in electric control of magnetic vortices in ferromagnetic nanodiscs. Nanoscale 2023; 15:707-717. [PMID: 36516064 DOI: 10.1039/d2nr02768b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
New high density storage media and spintronic devices come about with a progressing demand for the miniaturization of ferromagnetic structures. Vortex ordering of magnetic dipoles in such structures has been repeatedly observed as a stable state, offering the possibility of chirality in these states as a means to store information at high density. Electric pulses and magnetoelectric coupling are attractive options to control the chirality of such states in a deterministic manner. Here, we demonstrate the chirality reversal of vortex states in ferromagnetic nanodiscs via pulsed electric fields using a micromagnetic approach and focus on the analysis of the energetics of the reversal process. A strong thickness dependence of the chirality reversal in the nanodiscs is found that emanates from the anisotropy of the demagnetizing fields. Our results indicate that chiral switching of the magnetic moments in thin discs can give rise to a transient vortex-antivortex lattice not observed in thicker discs. This difference in the chirality reversal mechanism emanates from profoundly different energy barriers to overcome in thin and thicker discs. We also report the polarity-chirality correlation of a vortex that appears to depend on the aspect ratio of the nanodiscs.
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Affiliation(s)
- W A S Aldulaimi
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
| | - M B Okatan
- Department of Materials Science and Engineering, Izmir Institute of Technology, Gulbahce/Urla, 35430 Izmir, Turkey
| | - K Sendur
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
- Center of Excellence for Functional Surfaces and Interfaces for Nano-Diagnostics (EFSUN), Sabanci University, Orhanli, 34956, Tuzla, Istanbul, Turkey
| | - M C Onbasli
- Department of Electrical & Electronics Engineering, Koc University, 34450 Istanbul, Turkey
| | - I B Misirlioglu
- Faculty of Engineering and Natural Sciences, Sabanci University, Orhanli/Tuzla, 34956 Istanbul, Turkey.
- Center of Excellence for Functional Surfaces and Interfaces for Nano-Diagnostics (EFSUN), Sabanci University, Orhanli, 34956, Tuzla, Istanbul, Turkey
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Agar JC, Damodaran AR, Okatan MB, Kacher J, Gammer C, Vasudevan RK, Pandya S, Dedon LR, Mangalam RVK, Velarde GA, Jesse S, Balke N, Minor AM, Kalinin SV, Martin LW. Highly mobile ferroelastic domain walls in compositionally graded ferroelectric thin films. Nat Mater 2016; 15:549-556. [PMID: 26878312 DOI: 10.1038/nmat4567] [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: 07/21/2015] [Accepted: 01/18/2016] [Indexed: 06/05/2023]
Abstract
Domains and domain walls are critical in determining the response of ferroelectrics, and the ability to controllably create, annihilate, or move domains is essential to enable a range of next-generation devices. Whereas electric-field control has been demonstrated for ferroelectric 180° domain walls, similar control of ferroelastic domains has not been achieved. Here, using controlled composition and strain gradients, we demonstrate deterministic control of ferroelastic domains that are rendered highly mobile in a controlled and reversible manner. Through a combination of thin-film growth, transmission-electron-microscopy-based nanobeam diffraction and nanoscale band-excitation switching spectroscopy, we show that strain gradients in compositionally graded PbZr1-xTixO3 heterostructures stabilize needle-like ferroelastic domains that terminate inside the film. These needle-like domains are highly labile in the out-of-plane direction under applied electric fields, producing a locally enhanced piezoresponse. This work demonstrates the efficacy of novel modes of epitaxy in providing new modalities of domain engineering and potential for as-yet-unrealized nanoscale functional devices.
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Affiliation(s)
- J C Agar
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Department of Materials Science and Engineering, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - A R Damodaran
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - M B Okatan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - J Kacher
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - C Gammer
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R K Vasudevan
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S Pandya
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - L R Dedon
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - R V K Mangalam
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
| | - G A Velarde
- Department of Materials Science and Engineering, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | - S Jesse
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - N Balke
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A M Minor
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - S V Kalinin
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - L W Martin
- Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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Papandrew AB, Li Q, Okatan MB, Jesse S, Hartnett C, Kalinin SV, Vasudevan RK. Electrocatalysis-induced elasticity modulation in a superionic proton conductor probed by band-excitation atomic force microscopy. Nanoscale 2015; 7:20089-20094. [PMID: 26568116 DOI: 10.1039/c5nr04809e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Variable temperature band-excitation atomic force microscopy in conjunction with I-V spectroscopy was used to investigate the crystalline superionic proton conductor CsHSO4 during proton exchange induced by a Pt-coated conductive scanning probe. At a sample temperature of 150 °C and under an applied bias <1 V, reduction currents of up to 1 nA were observed. Simultaneously, we show that the electrochemical reactions are accompanied by a reversible decrease in the elastic modulus of CsHSO4, as seen by a contact resonance shift, and find evidence for superplasticity during scanning. These effects were not observed in the room-temperature phase of CsHSO4 or in the case of catalytically inactive conductive probes, proving the utility of this technique for monitoring electrochemical processes on the nanoscale, as well as the use of local contact stiffness as a sensitive indicator of electrochemical reactions.
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Affiliation(s)
- A B Papandrew
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
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Collins L, Okatan MB, Li Q, Kravenchenko II, Lavrik NV, Kalinin SV, Rodriguez BJ, Jesse S. Quantitative 3D-KPFM imaging with simultaneous electrostatic force and force gradient detection. Nanotechnology 2015; 26:175707. [PMID: 25851168 DOI: 10.1088/0957-4484/26/17/175707] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Kelvin probe force microscopy (KPFM) is a powerful characterization technique for imaging local electrochemical and electrostatic potential distributions and has been applied across a broad range of materials and devices. Proper interpretation of the local KPFM data can be complicated, however, by convolution of the true surface potential under the tip with additional contributions due to long range capacitive coupling between the probe (e.g. cantilever, cone, tip apex) and the sample under test. In this work, band excitation (BE)-KPFM is used to negate such effects. In contrast to traditional single frequency KPFM, multifrequency BE-KPFM is shown to afford dual sensitivity to both the electrostatic force and the force gradient detection, analogous to simultaneous amplitude modulated and frequency modulated KPFM imaging. BE-KPFM is demonstrated on a Pt/Au/SiO(x) test structure and electrostatic force gradient detection is found to lead to an improved lateral resolution compared to electrostatic force detection. Finally, a 3D-KPFM imaging technique is developed. Force volume (FV) BE-KPFM allows the tip-sample distance dependence of the electrostatic interactions (force and force gradient) to be recorded at each point across the sample surface. As such, FVBE-KPFM provides a much needed pathway towards complete tip-sample capacitive de-convolution in KPFM measurements and will enable quantitative surface potential measurements with nanoscale resolution.
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Affiliation(s)
- L Collins
- School of Physics, University College Dublin, Belfield, Dublin 4, Ireland. Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Collins L, Tselev A, Jesse S, Okatan MB, Proksch R, Mathews JP, Mitchell GD, Rodriguez BJ, Kalinin SV, Ivanov IN. Breaking the limits of structural and mechanical imaging of the heterogeneous structure of coal macerals. Nanotechnology 2014; 25:435402. [PMID: 25299223 DOI: 10.1088/0957-4484/25/43/435402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The correlation between local mechanical (elasto-plastic) and structural (composition) properties of coal presents significant fundamental and practical interest for coal processing and for the development of rheological models of coal to coke transformations. Here, we explore the relationship between the local structural, chemical composition, and mechanical properties of coal using a combination of confocal micro-Raman imaging and band excitation atomic force acoustic microscopy for a bituminous coal. This allows high resolution imaging (10s of nm) of mechanical properties of the heterogeneous (banded) architecture of coal and correlating them to the optical gap, average crystallite size, the bond-bending disorder of sp(2) aromatic double bonds, and the defect density. This methodology allows the structural and mechanical properties of coal components (lithotypes, microlithotypes, and macerals) to be understood, and related to local chemical structure, potentially allowing for knowledge-based modeling and optimization of coal utilization processes.
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Affiliation(s)
- L Collins
- School of Physics, University College Dublin, Belfield, Dublin 4, Ireland. Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Belfield, Dublin 4, Ireland
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Okatan MB, Roytburd AL, Nagarajan V, Alpay SP. Electrical domain morphologies in compositionally graded ferroelectric films. J Phys Condens Matter 2012; 24:024215. [PMID: 22173488 DOI: 10.1088/0953-8984/24/2/024215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a nonlinear thermodynamic formalism coupled with an electrostatic analysis of uniaxial n-layered compositionally graded heteroepitaxial ferroelectric films and extend this formalism to continuously graded ferroelectric films. We show that the domain morphology and its subsequent evolution in the presence of an electric field are determined by the spontaneous polarisation of the film induced through the compositional grading. The results for compositionally graded epitaxial (001) (Ba,Sr)TiO(3) and (001) Pb(Zr,Ti)O(3) films on (001)SrTiO(3) demonstrate that, while the domain morphologies in these two films are different in appearance, the dielectric displacement and the dielectric permittivity of such graded ferroelectric films exhibit a strong nonlinear behaviour which results in a high dielectric tunability. These findings indicate that it is possible to design specific domain structures that will yield desirable dielectric properties by controlling the strength of the compositional grading in the films.
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Affiliation(s)
- M B Okatan
- School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
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