The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
A L Kholkin - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Theory of strain mediated direct magnetoelectric effect in multiferroic film substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
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Thermodynamic Theory of strain-mediated direct magnetoelectric effect in multiferroic film–substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
N A Pertsev - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Theory of strain mediated direct magnetoelectric effect in multiferroic film substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
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Thermodynamic Theory of strain-mediated direct magnetoelectric effect in multiferroic film–substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
X. L. Li - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Theory of growth of nanostructures
Progress in Materials Science, 2014Co-Authors: X. L. Li, C X Wang, G. W. YangAbstract:Abstract Self-assembled nanostructures, such as quantum dots (QDs), quantum rings (QRs) and nanowires (NWs), have been extensively studied because of their physical properties and promising device applications. To improve their physical properties and device applications, the fabrication of nanostructures with a uniform size, proper shape and regular position is desired in nanotechnology. Therefore, investigations of the growth process of nanostructures are highly important to control the self-assembly and synthesis processes of nanostructures flexibly. Thermodynamic Theory as a universal approach to investigate material growth has been widely used to study the growth of nanostructures. This review covers the Thermodynamic theoretical treatments of the growth of nanostructures, including QDs by epitaxy, QRs by droplet epitaxy, and NWs by the vapor–liquid–solid (VLS) mechanism. First, we introduce the Thermodynamic models of the growth mechanisms of QDs by self-assembled epitaxy. The formation, stability, shape and position of QDs are discussed. Second, we introduce the nucleation Thermodynamics and the growth kinetics of QRs by droplet epitaxy, and we present a simulation method employing the shape evolution of QRs based on a kinetic model. Third, several theoretical tools are introduced to address the nucleation and growth of NW by the VLS process. Finally, we introduce a Thermodynamic treatment including the thermal fluctuations within the context of a statistical mechanical and quantum mechanical model for the temperature-dependent growth of nanostructures.
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Thermodynamic Theory of Quantum Dot Self-Assembly on Strained Substrates
Journal of Physical Chemistry C, 2010Co-Authors: X. L. LiAbstract:A quantitative Thermodynamic Theory has been established to investigate the self-assembly of quantum dots (QDs) on strained substrates. It was found that the driving force of QD formation on strained substrates is different from that on common substrates without extra surface strain. The different driving force results in a smaller critical thickness of wetting layer and a lower barrier energy of QD formation on strained substrates than that on common substrates. The theoretical results not only are in good agreement with the experimental observations but also reveal physical mechanisms involved in the QD self-assembly on strained substrates, which implies that the established Thermodynamic Theory could be expected to be applicable to address the self-assembly of quantum dots on strained substrates.
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Thermodynamic Theory of shape evolution induced by Si capping in Ge quantum dot self-assembly
Journal of Applied Physics, 2009Co-Authors: X. L. Li, G. W. YangAbstract:A quantitative Thermodynamic Theory has been established to investigate the shape evolution mechanisms induced by Si capping in Ge quantum dot self-assembly. It was found that the decrease in Ge concentration of the quantum dot induced by Si absorption breaks the original balance of composition between the quantum dot and wetting layer. In order to create a new balance, the wetting layer is required to increase its thickness through the Ge diffusion from the quantum dot to the wetting layer, which leads to the shape evolution of the growing quantum dot. The Ge diffusion can suppress the expansion of quantum dots and promote their shrinkage. The theoretical results not only are in well agreement with the experimental observations but also reveal physical mechanisms involved in the Ge quantum dot self-assembly induced by Si capping, which implies that the established Thermodynamic Theory could be expected to be applicable to address the capping-assisted self-assembly of quantum dots.
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A Thermodynamic Theory of the self-assembly of quantum dots
New Journal of Physics, 2008Co-Authors: X. L. Li, Gang Ouyang, G. W. YangAbstract:We establish a general Thermodynamic model to address the self-assembly of quantum dots (QDs) in heterogeneous epitaxial systems by taking into account the size-dependent surface and interface energies and the interactions between QDs. The proposed Thermodynamic Theory not only elucidates the growth mechanisms of the QD formation at a critical coverage and the physical origins of the narrow size distribution of QDs, but also predicts two important critical sizes in the QD growth: one is the critical size of the QD formation and the other is the critical size of the stable array of QDs. The theoretical results are in good agreement with the experimental observations, which implies that the established Thermodynamic Theory could be expected to be a general approach to pursue the physical mechanisms of self-assembly of QDs.
V G Kukhar - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Theory of strain mediated direct magnetoelectric effect in multiferroic film substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
-
Thermodynamic Theory of strain-mediated direct magnetoelectric effect in multiferroic film–substrate hybrids
Nanotechnology, 2010Co-Authors: V G Kukhar, N A Pertsev, A L KholkinAbstract:A nonlinear Thermodynamic Theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric–ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the Thermodynamic Theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO3 and PbTiO3 films deposited on Co0.8Zn0.2Fe2O4, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO3 and PbTiO3 films deposited on Terfenol-D, the calculations yield high ME polarization coefficients ~ 10 − 7 s m − 1 and giant ME voltage coefficients ~ 50 V cm − 1 Oe − 1.
G. W. Yang - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic Theory of growth of nanostructures
Progress in Materials Science, 2014Co-Authors: X. L. Li, C X Wang, G. W. YangAbstract:Abstract Self-assembled nanostructures, such as quantum dots (QDs), quantum rings (QRs) and nanowires (NWs), have been extensively studied because of their physical properties and promising device applications. To improve their physical properties and device applications, the fabrication of nanostructures with a uniform size, proper shape and regular position is desired in nanotechnology. Therefore, investigations of the growth process of nanostructures are highly important to control the self-assembly and synthesis processes of nanostructures flexibly. Thermodynamic Theory as a universal approach to investigate material growth has been widely used to study the growth of nanostructures. This review covers the Thermodynamic theoretical treatments of the growth of nanostructures, including QDs by epitaxy, QRs by droplet epitaxy, and NWs by the vapor–liquid–solid (VLS) mechanism. First, we introduce the Thermodynamic models of the growth mechanisms of QDs by self-assembled epitaxy. The formation, stability, shape and position of QDs are discussed. Second, we introduce the nucleation Thermodynamics and the growth kinetics of QRs by droplet epitaxy, and we present a simulation method employing the shape evolution of QRs based on a kinetic model. Third, several theoretical tools are introduced to address the nucleation and growth of NW by the VLS process. Finally, we introduce a Thermodynamic treatment including the thermal fluctuations within the context of a statistical mechanical and quantum mechanical model for the temperature-dependent growth of nanostructures.
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Thermodynamic Theory of shape evolution induced by Si capping in Ge quantum dot self-assembly
Journal of Applied Physics, 2009Co-Authors: X. L. Li, G. W. YangAbstract:A quantitative Thermodynamic Theory has been established to investigate the shape evolution mechanisms induced by Si capping in Ge quantum dot self-assembly. It was found that the decrease in Ge concentration of the quantum dot induced by Si absorption breaks the original balance of composition between the quantum dot and wetting layer. In order to create a new balance, the wetting layer is required to increase its thickness through the Ge diffusion from the quantum dot to the wetting layer, which leads to the shape evolution of the growing quantum dot. The Ge diffusion can suppress the expansion of quantum dots and promote their shrinkage. The theoretical results not only are in well agreement with the experimental observations but also reveal physical mechanisms involved in the Ge quantum dot self-assembly induced by Si capping, which implies that the established Thermodynamic Theory could be expected to be applicable to address the capping-assisted self-assembly of quantum dots.
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A Thermodynamic Theory of the self-assembly of quantum dots
New Journal of Physics, 2008Co-Authors: X. L. Li, Gang Ouyang, G. W. YangAbstract:We establish a general Thermodynamic model to address the self-assembly of quantum dots (QDs) in heterogeneous epitaxial systems by taking into account the size-dependent surface and interface energies and the interactions between QDs. The proposed Thermodynamic Theory not only elucidates the growth mechanisms of the QD formation at a critical coverage and the physical origins of the narrow size distribution of QDs, but also predicts two important critical sizes in the QD growth: one is the critical size of the QD formation and the other is the critical size of the stable array of QDs. The theoretical results are in good agreement with the experimental observations, which implies that the established Thermodynamic Theory could be expected to be a general approach to pursue the physical mechanisms of self-assembly of QDs.
