The Experts below are selected from a list of 1002 Experts worldwide ranked by ideXlab platform
Scott Sutherland - One of the best experts on this subject based on the ideXlab platform.
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On Brillouin Zones
Communications in Mathematical Physics, 2000Co-Authors: J. J. P. Veerman, M. M. Peixoto, André C. Rocha, Scott SutherlandAbstract:Brillouin Zones were introduced by Brillouin in the thirties to describe quantum mechanical properties of crystals, that is, in a lattice in $\R^n$. They play an important role in solid-state physics. It was shown by Bieberbach that Brillouin Zones tile the underlying space and that each zone has the same area. We generalize the notion of Brillouin Zones to apply to an arbitrary discrete set in a proper metric space, and show that analogs of Bieberbach's results hold in this context. We then use these ideas to discuss focusing of geodesics in orbifolds of constant curvature. In the particular case of the Riemann surfaces H^2/Gamma(k), (k=2,3, or 5), we explicitly count the number of geodesics of length t that connect the point i to itself.
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On Brillouin Zones
Communications in Mathematical Physics, 2000Co-Authors: J. J. P. Veerman, M. M. Peixoto, André C. Rocha, Scott SutherlandAbstract:Brillouin Zones were introduced by Brillouin [Br] in the thirties to describe quantum mechanical properties of crystals, that is, in a lattice in ℝn. They play an important role in solid-state physics. It was shown by Bieberbach [Bi] that Brillouin Zones tile the underlying space and that each zone has the same area. We generalize the notion of Brillouin Zones to apply to an arbitrary discrete set in a proper metric space, and show that analogs of Bieberbach's results hold in this context.
Isao Tanaka - One of the best experts on this subject based on the ideXlab platform.
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distributions of phonon lifetimes in Brillouin Zones
Physical Review B, 2015Co-Authors: Atsushi Togo, Laurent Chaput, Isao TanakaAbstract:Lattice thermal conductivities of zincblende- and wurtzite-type compounds with 33 combinations of elements are calculated with the single-mode relaxation-time approximation and linearized phonon Boltzmann equation from first-principles anharmonic lattice dynamics calculations. In 9 zincblende-type compounds, distributions of phonon linewidths (inverse phonon lifetimes) are discussed in detail. The phonon linewidths vary non-smoothly with respect to wave vector, which is explained from the imaginary parts of the self energies. It is presented that detailed combination of phonon-phonon interaction strength and three phonon selection rule is critically important to determine phonon lifetime for these compounds. This indicates difficulty to predict phonon lifetime quantitatively without anharmonic force constants. However it is shown that joint density of states weighted by phonon numbers, which is calculated only from harmonic force constants, can be potentially used for a screening of the lattice thermal conductivity of materials.
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distributions of phonon lifetimes in Brillouin Zones
Physical Review B, 2015Co-Authors: Atsushi Togo, Laurent Chaput, Isao TanakaAbstract:A collaboration of researchers from Japan and France present a comprehensive study of phonon lifetimes and thermal conductivity for 33 zincblende- and wurtzite compounds using linearized phonon Boltzmann equation and first-principles anharmonic phonon calculations. The software that the authors created for this study will be released as an open source package and should be of help in the search of new materials for thermoelectric applications.
J. J. P. Veerman - One of the best experts on this subject based on the ideXlab platform.
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On Brillouin Zones
Communications in Mathematical Physics, 2000Co-Authors: J. J. P. Veerman, M. M. Peixoto, André C. Rocha, Scott SutherlandAbstract:Brillouin Zones were introduced by Brillouin in the thirties to describe quantum mechanical properties of crystals, that is, in a lattice in $\R^n$. They play an important role in solid-state physics. It was shown by Bieberbach that Brillouin Zones tile the underlying space and that each zone has the same area. We generalize the notion of Brillouin Zones to apply to an arbitrary discrete set in a proper metric space, and show that analogs of Bieberbach's results hold in this context. We then use these ideas to discuss focusing of geodesics in orbifolds of constant curvature. In the particular case of the Riemann surfaces H^2/Gamma(k), (k=2,3, or 5), we explicitly count the number of geodesics of length t that connect the point i to itself.
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On Brillouin Zones
Communications in Mathematical Physics, 2000Co-Authors: J. J. P. Veerman, M. M. Peixoto, André C. Rocha, Scott SutherlandAbstract:Brillouin Zones were introduced by Brillouin [Br] in the thirties to describe quantum mechanical properties of crystals, that is, in a lattice in ℝn. They play an important role in solid-state physics. It was shown by Bieberbach [Bi] that Brillouin Zones tile the underlying space and that each zone has the same area. We generalize the notion of Brillouin Zones to apply to an arbitrary discrete set in a proper metric space, and show that analogs of Bieberbach's results hold in this context.
Smolyaninov Igor - One of the best experts on this subject based on the ideXlab platform.
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Self-assembled tunable photonic hyper-crystals
'Purdue University (bepress)', 2014Co-Authors: Smolyaninova, Vera N., Yost Bradley, Lhneman David, Narimanov Evgenii, Smolyaninov IgorAbstract:We demonstrate a novel artificial optical material, the photonic hyper-crystal\u27\u27, which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin Zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing
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Self-assembled tunable photonic hyper-crystals
2013Co-Authors: Smolyaninova, Vera N., Yost Bradley, Lahneman David, Narimanov, Evgenii E., Smolyaninov IgorAbstract:We demonstrate a novel artificial optical material, a photonic hyper-crystal, which combines the most interesting features of hyperbolic metamaterials and photonic crystals. Similar to hyperbolic metamaterials, photonic hyper-crystals exhibit broadband divergence in their photonic density of states due to the lack of usual diffraction limit on the photon wave vector. On the other hand, similar to photonic crystals, hyperbolic dispersion law of extraordinary photons is modulated by forbidden gaps near the boundaries of photonic Brillouin Zones. Three dimensional self-assembly of photonic hyper-crystals has been achieved by application of external magnetic field to a cobalt nanoparticle-based ferrofluid. Unique spectral properties of photonic hyper-crystals lead to extreme sensitivity of the material to monolayer coatings of cobalt nanoparticles, which should find numerous applications in biological and chemical sensing.Comment: 24 pages, 6 figure
Atsushi Togo - One of the best experts on this subject based on the ideXlab platform.
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distributions of phonon lifetimes in Brillouin Zones
Physical Review B, 2015Co-Authors: Atsushi Togo, Laurent Chaput, Isao TanakaAbstract:Lattice thermal conductivities of zincblende- and wurtzite-type compounds with 33 combinations of elements are calculated with the single-mode relaxation-time approximation and linearized phonon Boltzmann equation from first-principles anharmonic lattice dynamics calculations. In 9 zincblende-type compounds, distributions of phonon linewidths (inverse phonon lifetimes) are discussed in detail. The phonon linewidths vary non-smoothly with respect to wave vector, which is explained from the imaginary parts of the self energies. It is presented that detailed combination of phonon-phonon interaction strength and three phonon selection rule is critically important to determine phonon lifetime for these compounds. This indicates difficulty to predict phonon lifetime quantitatively without anharmonic force constants. However it is shown that joint density of states weighted by phonon numbers, which is calculated only from harmonic force constants, can be potentially used for a screening of the lattice thermal conductivity of materials.
-
distributions of phonon lifetimes in Brillouin Zones
Physical Review B, 2015Co-Authors: Atsushi Togo, Laurent Chaput, Isao TanakaAbstract:A collaboration of researchers from Japan and France present a comprehensive study of phonon lifetimes and thermal conductivity for 33 zincblende- and wurtzite compounds using linearized phonon Boltzmann equation and first-principles anharmonic phonon calculations. The software that the authors created for this study will be released as an open source package and should be of help in the search of new materials for thermoelectric applications.