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X L - One of the best experts on this subject based on the ideXlab platform.
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evolution of flux Closure Domain arrays in oxide multilayers with misfit strain
Acta Materialia, 2019Co-Authors: Yuanhao Wang, Yinlian Zhu, Yunlong Tang, Ying Liu, J Y, M J Han, X LAbstract:Abstract Ferroelectric flux-Closure Domains have attracted great attention due to their potentials in high density data storage. For their future applications, it is important to understand their evolution with different factors, such as misfit strain. In this work, a flux-Closure Domain consisting of a vertical 180° Domain wall with two symmetric a Domains in both ends (“I” type Closure) was observed in nearly unstrained SrTiO3/PbTiO3 multilayers by aberration corrected Transmission Electron Microscopy, which was speculated to be mainly induced by the strong depolarization field near the interface. With the tensile strain increasing, the small a Domains in “I” type flux-Closures grow gradually and eventually change to the well-known “V” type flux-Closures. On the basis of a combination of experimental results and phase field simulations, the phase diagram of the stabilized Domain arrays versus the strains in PbTiO3 films are established. These results provide significant information on understanding the formation mechanism of flux-Closure Domains and shed light on their controlled growth. In addition, it paves a way to reduce the economic cost in their commercial applications because the SrTiO3 substrate is easy to synthesize and much cheaper than scandate substrates.
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large scale two dimensional flux Closure Domain arrays in oxide multilayers and their controlled growth
Nano Letters, 2017Co-Authors: Ying Liu, Yinlian Zhu, Yunlong Tang, X L, Yujia Wang, Chihou Lei, Sirui ZhangAbstract:Ferroelectric flux-Closures are very promising in high-density storage and other nanoscale electronic devices. To make the data bits addressable, the nanoscale flux-Closures are required to be periodic via a controlled growth. Although flux-Closure quadrant arrays with 180° Domain walls perpendicular to the interfaces (V-Closure) have been observed in strained ferroelectric PbTiO3 films, the flux-Closure quadrants therein are rather asymmetric. In this work, we report not only a periodic array of the symmetric flux-Closure quadrants with 180° Domain walls parallel to the interfaces (H-Closure) but also a large scale alternative stacking of the V- and H-Closure arrays in PbTiO3/SrTiO3 multilayers. On the basis of a combination of aberration-corrected scanning transmission electron microscopic imaging and phase field modeling, we establish the phase diagram in the layer-by-layer two-dimensional arrays versus the thickness ratio of adjacent PbTiO3 films, in which energy competitions play dominant roles. The ...
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3d polarization texture of a symmetric 4 fold flux Closure Domain in strained ferroelectric pbtio3 films
Journal of Materials Research, 2017Co-Authors: Yunlong Tang, Yinlian Zhu, Ying Liu, Zijian Hong, E A Eliseev, Anna N Morozovska, Yujia Wang, Longqing Chen, Stephen J Pennycook, X LAbstract:Although the strong coupling of polarization to spontaneous strain in ferroelectrics would impart a flux-Closure with severe disclination strains, recent studies have successfully stabilized such a Domain via a nano-scaled multi-layer growth. Nonetheless, the detailed distributions of polarizations in three-dimensions (3D) and how the strains inside a flux Closure affect the structures of Domain walls are still less understood. Here we report a 3D polarization texture of a 4-fold flux Closure Domain identified in tensile strained ferroelectric PbTiO 3 /SrTiO 3 multilayer films. Ferroelectric displacement analysis based on aberration-corrected scanning transmission electron microscopic imaging reveals highly inhomogeneous strains with strain gradient above 10 7 /m. These giant disclination strains significantly broaden the 90° Domain walls, while the flexoelectric coupling at 180° Domain wall is less affected. The present observations are helpful for understanding the basics of topological dipole textures and indicate novel applications of ferroelectrics through engineering strains.
M Kladivova - One of the best experts on this subject based on the ideXlab platform.
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dynamics of Domain wall depinning from Closure Domain structure at the end of bistable glass coated microwire
Journal of Magnetism and Magnetic Materials, 2020Co-Authors: J. Ziman, J. Onufer, M KladivovaAbstract:Abstract The study of Closure Domain structure dynamics at the end of magnetic bistable glass-coated microwire is presented. The method in which critical parameters of the so-called three-level rectangular field pulse are measured is used. It is shown that dependences measured using three-level field pulses cannot be satisfactorily interpreted by the model in which application of a rectangular field pulse causes the release of a single Domain wall from a potential well. A new model based on the simplest possible Closure Domain structures at the microwire end is proposed. In the framework of this model the application of a non-zero first-level field results in changes in Domain wall parameters (inertial mass and mobility) which have opposite effects on the prolonging/shortening of critical field pulse width and do not provide satisfactory explanation of experimental observations. Shortening of the path which the wall has to move along to become free can result from the wall lengthening caused by application of the non-zero first-level field. This effect combined with position-independent force acting on the wall can explain the observed behaviour. Modelling of this process is also presented and supports this interpretation.
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stress induced changes in Closure Domain structure dynamics in bistable ferromagnetic microwire
Acta Physica Polonica A, 2014Co-Authors: J. Onufer, J. Ziman, M KladivovaAbstract:A new experimental method for the study of Closure Domain structure dynamics in bistable ferromagnetic microwires is proposed. The simple experimental set-up enables detection of the presence of a free Domain wall in the wire after application of a well-de ned rectangular magnetic eld pulse. The changes in Closure Domain structure dynamics, caused by applied tensile stress, are demonstrated by measurements on Fe77.5B15Si7.5 glasscoated microwire. Minimum critical eld for the release of a Domain wall from the Closure Domain structure increases with increasing stress, while on the other hand, the minimum time needed for this process rapidly decreases with increasing stress.
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dynamics of Closure Domain structure in bistable ferromagnetic microwire
Journal of Magnetism and Magnetic Materials, 2013Co-Authors: J. Onufer, J. Ziman, M KladivovaAbstract:Abstract Dynamics of Closure Domain structure in bistable glass-coated Fe 77.5 B 15 Si 7.5 amorphous ferromagnetic microwire was studied experimentally and theoretically. A new experiment for this study was proposed. The basic idea of this consisted in checking whether a well-defined rectangular magnetic field pulse applied to the microwire end can produce a stable and free Domain wall in the microwire. A theoretical model previously used for describing the wall depinning process from the wire end was adapted for interpretation of our experimental results. Information about parameters of the potential well in which the wall is initially trapped as well as about wall dynamics was obtained. Values of these parameters are in good agreement with those obtained from different types of experiments.
S O Demokritov - One of the best experts on this subject based on the ideXlab platform.
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micro brillouin light scattering spectroscopy of magnetic nanostructures
IEEE Transactions on Magnetics, 2008Co-Authors: S O Demokritov, V E DemidovAbstract:We describe a new technique, micro-Brillouin light scattering spectroscopy, for investigation of spin wave dynamics in magnetic nanostructures. The technique offers advantages for studies of small magnetic squares with Closure Domain structure and magnetic nanoelements similar to those used in magnetic random access memory. The technique is particularly effective in two-dimensional mapping of spin waves excited by a single nanocontact due to the spin torque transfer effect.
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spin wave eigenmodes of permalloy squares with a Closure Domain structure
Physical Review Letters, 2005Co-Authors: Korbinian Perzlmaier, B Hillebrands, V E Demidov, Matthias Buess, C H Back, S O DemokritovAbstract:Quantized spin-wave eigenmodes in single, 16 nm thick and 0.75 to 4 µm wide square permalloy islands with a fourfold Closure Domain structure have been investigated by microfocus Brillouin light scattering spectroscopy and time resolved scanning magneto-optical Kerr microscopy. Up to six eigenmodes were detected and classified. The main direction of the spin-wave quantization in the Domains was found to be perpendicular to the local static magnetization. An additional less pronounced quantization along the direction parallel to the static magnetization was also observed.
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spin wave eigenmodes of permalloy squares with a Closure Domain structure
Physical Review Letters, 2005Co-Authors: Korbinian Perzlmaier, B Hillebrands, V E Demidov, Matthias Buess, C H Back, S O DemokritovAbstract:Quantized spin-wave eigenmodes in single, 16 nm thick and 0.75 to $4\text{ }\ensuremath{\mu}\mathrm{m}$ wide square permalloy islands with a fourfold Closure Domain structure have been investigated by microfocus Brillouin light scattering spectroscopy and time resolved scanning magneto-optical Kerr microscopy. Up to six eigenmodes were detected and classified. The main direction of the spin-wave quantization in the Domains was found to be perpendicular to the local static magnetization. An additional less pronounced quantization along the direction parallel to the static magnetization was also observed.
J M Gregg - One of the best experts on this subject based on the ideXlab platform.
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mesoscale flux Closure Domain formation in single crystal batio3
Nature Communications, 2011Co-Authors: R G P Mcquaid, L J Mcgilly, Pankaj Sharma, Alexei Gruverman, J M GreggAbstract:Over 60 years ago, Charles Kittel predicted that quadrant Domains should spontaneously form in small ferromagnetic platelets. He expected that the direction of magnetization within each quadrant should lie parallel to the platelet surface, minimizing demagnetizing fields,and that magnetic moments should be configured into an overall closed loop, or flux-Closure arrangement. Although now a ubiquitous observation in ferromagnets, obvious flux-Closure patterns have been somewhat elusive in ferroelectric materials. This is despite the analogous behaviour between these two ferroic subgroups and the recent prediction of dipole Closure states by atomistic simulations research. Here we show Piezoresponse Force Microscopy images of mesoscopic dipole Closure patterns in free-standing, single-crystal lamellae of BaTiO(3). Formation of these patterns is a dynamical process resulting from system relaxation after the BaTiO(3) has been poled with a uniform electric field. The flux-Closure states are composed of shape conserving 90° stripe Domains which minimize disclination stresses.
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mesoscale flux Closure Domain formation in single crystal batio 3
Nature Communications, 2011Co-Authors: R G P Mcquaid, L J Mcgilly, Pankaj Sharma, Alexei Gruverman, J M GreggAbstract:Over 60 years ago, Charles Kittel predicted that quadrant Domains should spontaneously form in small ferromagnetic platelets. He expected that the direction of magnetization within each quadrant should lie parallel to the platelet surface, minimizing demagnetizing fields,and that magnetic moments should be configured into an overall closed loop, or flux-Closure arrangement. Although now a ubiquitous observation in ferromagnets, obvious flux-Closure patterns have been somewhat elusive in ferroelectric materials. This is despite the analogous behaviour between these two ferroic subgroups and the recent prediction of dipole Closure states by atomistic simulations research. Here we show Piezoresponse Force Microscopy images of mesoscopic dipole Closure patterns in free-standing, single-crystal lamellae of BaTiO3. Formation of these patterns is a dynamical process resulting from system relaxation after the BaTiO3 has been poled with a uniform electric field. The flux-Closure states are composed of shape conserving 90° stripe Domains which minimize disclination stresses.
Yunlong Tang - One of the best experts on this subject based on the ideXlab platform.
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real time observation of phase coexistence and a1 a2 to flux Closure Domain transformation in ferroelectric films
Acta Materialia, 2020Co-Authors: Yuezhao Wang, Yunlong Tang, Y L Zhu, Miaomiao Han, M J Zou, Yuxia Feng, Ningbin ZhangAbstract:Abstract Phase coexistence in ferroelectric oxide films displays complex phase competitions and transformation which suggest new multiple-coupled properties. Here we have successfully engineered the coexistence of flux-Closure and a1/a2 phases in tensile-strained PbTiO3 films sandwiched between GdScO3 substrate and a SrTiO3 layer. Moreover, by using in-situ electron beam illumination, the unusual transformation from a1/a2 phase to the flux-Closure phase was directly observed. In detail, there are two types of transformations: One is the nucleation, growth, and expansion of the flux-Closure phase from the internal region of the a1/a2 phase. The other feature is a “dislocation gliding” like behavior: a thin lamella of a1/a2 shrinks like “partial dislocation pairs” and finally the gradually disappeared a1/a2 lamella forms a “perfect dislocation” in the flux-Closure Domain matrix. Phase-field simulations suggest that the a1/a2 to flux-Closure transition is induced by the decrease of the depolarization field, which is screened by the injected electrons from electron beam irradiation. These results directly confirm the phase interconversion under an external stimulus at the nanometer scale, which shed new light on the fabrication of new polar textures.
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evolution of flux Closure Domain arrays in oxide multilayers with misfit strain
Acta Materialia, 2019Co-Authors: Yuanhao Wang, Yinlian Zhu, Yunlong Tang, Ying Liu, J Y, M J Han, X LAbstract:Abstract Ferroelectric flux-Closure Domains have attracted great attention due to their potentials in high density data storage. For their future applications, it is important to understand their evolution with different factors, such as misfit strain. In this work, a flux-Closure Domain consisting of a vertical 180° Domain wall with two symmetric a Domains in both ends (“I” type Closure) was observed in nearly unstrained SrTiO3/PbTiO3 multilayers by aberration corrected Transmission Electron Microscopy, which was speculated to be mainly induced by the strong depolarization field near the interface. With the tensile strain increasing, the small a Domains in “I” type flux-Closures grow gradually and eventually change to the well-known “V” type flux-Closures. On the basis of a combination of experimental results and phase field simulations, the phase diagram of the stabilized Domain arrays versus the strains in PbTiO3 films are established. These results provide significant information on understanding the formation mechanism of flux-Closure Domains and shed light on their controlled growth. In addition, it paves a way to reduce the economic cost in their commercial applications because the SrTiO3 substrate is easy to synthesize and much cheaper than scandate substrates.
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large scale two dimensional flux Closure Domain arrays in oxide multilayers and their controlled growth
Nano Letters, 2017Co-Authors: Ying Liu, Yinlian Zhu, Yunlong Tang, X L, Yujia Wang, Chihou Lei, Sirui ZhangAbstract:Ferroelectric flux-Closures are very promising in high-density storage and other nanoscale electronic devices. To make the data bits addressable, the nanoscale flux-Closures are required to be periodic via a controlled growth. Although flux-Closure quadrant arrays with 180° Domain walls perpendicular to the interfaces (V-Closure) have been observed in strained ferroelectric PbTiO3 films, the flux-Closure quadrants therein are rather asymmetric. In this work, we report not only a periodic array of the symmetric flux-Closure quadrants with 180° Domain walls parallel to the interfaces (H-Closure) but also a large scale alternative stacking of the V- and H-Closure arrays in PbTiO3/SrTiO3 multilayers. On the basis of a combination of aberration-corrected scanning transmission electron microscopic imaging and phase field modeling, we establish the phase diagram in the layer-by-layer two-dimensional arrays versus the thickness ratio of adjacent PbTiO3 films, in which energy competitions play dominant roles. The ...
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3d polarization texture of a symmetric 4 fold flux Closure Domain in strained ferroelectric pbtio3 films
Journal of Materials Research, 2017Co-Authors: Yunlong Tang, Yinlian Zhu, Ying Liu, Zijian Hong, E A Eliseev, Anna N Morozovska, Yujia Wang, Longqing Chen, Stephen J Pennycook, X LAbstract:Although the strong coupling of polarization to spontaneous strain in ferroelectrics would impart a flux-Closure with severe disclination strains, recent studies have successfully stabilized such a Domain via a nano-scaled multi-layer growth. Nonetheless, the detailed distributions of polarizations in three-dimensions (3D) and how the strains inside a flux Closure affect the structures of Domain walls are still less understood. Here we report a 3D polarization texture of a 4-fold flux Closure Domain identified in tensile strained ferroelectric PbTiO 3 /SrTiO 3 multilayer films. Ferroelectric displacement analysis based on aberration-corrected scanning transmission electron microscopic imaging reveals highly inhomogeneous strains with strain gradient above 10 7 /m. These giant disclination strains significantly broaden the 90° Domain walls, while the flexoelectric coupling at 180° Domain wall is less affected. The present observations are helpful for understanding the basics of topological dipole textures and indicate novel applications of ferroelectrics through engineering strains.