The Experts below are selected from a list of 71349 Experts worldwide ranked by ideXlab platform
S Stringari - One of the best experts on this subject based on the ideXlab platform.
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superstripes and the Excitation Spectrum of a spin orbit coupled bose einstein condensate
Physical Review Letters, 2013Co-Authors: Giovanni I Martone, L P Pitaevskii, S StringariAbstract:Using Bogoliubov theory we calculate the Excitation Spectrum of a spinor Bose-Einstein condensed gas with an equal Rashba and Dresselhaus spin-orbit coupling in the stripe phase. The emergence of a double gapless band structure is pointed out as a key signature of Bose-Einstein condensation and of the spontaneous breaking of translational invariance symmetry. In the long wavelength limit the lower and upper branches exhibit, respectively, a clear spin and density nature. For wave vectors close to the first Brillouin zone, the lower branch acquires an important density character responsible for the divergent behavior of the structure factor and of the static response function, reflecting the occurrence of crystalline order. The sound velocities are calculated as functions of the Raman coupling for Excitations propagating orthogonal and parallel to the stripes. Our predictions provide new perspectives for the identification of supersolid phenomena in ultracold atomic gases.
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anisotropic dynamics of a spin orbit coupled bose einstein condensate
Physical Review A, 2012Co-Authors: Giovanni I Martone, L P Pitaevskii, S StringariAbstract:By calculating the density response function we identify the Excitation Spectrum of a Bose-Einstein condensate with equal Rashba and Dresselhaus spin-orbit coupling. We find that the velocity of sound along the direction of spin-orbit coupling is deeply quenched and vanishes when one approaches the second-order phase transition between the plane-wave and the zero momentum quantum phases. We also point out the emergence of a roton minimum in the Excitation Spectrum for small values of the Raman coupling, providing the onset of the transition to the stripe phase. Our findings point out the occurrence of a strong anisotropy in the dynamic behavior of the gas. A hydrodynamic description accounting for the collective oscillations in both uniform and harmonically trapped gases is also derived.
Michael Hinczewski - One of the best experts on this subject based on the ideXlab platform.
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Excitation Spectrum gap and spin wave velocity of xxz heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic Excitation Spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the antiferromagnetic XXZ chain: an antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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Excitation Spectrum gap and spin wave velocity of x x z heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic $XXZ$ spin-$\frac{1}{2}$ Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated throughout the entire temperature and anisotropy ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the antiferromagnetic spin-liquid spin-wave velocity and the Ising-like ferromagnetic Excitation Spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction ${s}_{i}^{x}{s}_{j}^{x}+{s}_{i}^{y}{s}_{j}^{y}$ induces an antiferromagnetic correlation in the out-of-plane ${s}_{i}^{z}$ component, at higher temperatures in the antiferromagnetic $XXZ$ chain, dominantly at low temperatures in the ferromagnetic $XXZ$ chain, and, in-between, at all temperatures in the $XY$ chain. We find that the converse effect also occurs in the antiferromagnetic $XXZ$ chain: an antiferromagnetic ${s}_{i}^{z}{s}_{j}^{z}$ interaction induces a correlation in the ${s}_{i}^{xy}$ component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or $XY$) of anisotropy; and (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
D M Basko - One of the best experts on this subject based on the ideXlab platform.
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probing the band structure of quadri layer graphene with magneto phonon resonance
New Journal of Physics, 2012Co-Authors: C Faugeras, P Kossacki, A A L Nicolet, M Orlita, M Potemski, Ather Mahmood, D M BaskoAbstract:We show how the magneto-phonon resonance, particularly pronounced in sp2 carbon allotropes, can be used as a tool to probe the band structure of multilayer graphene specimens. Even when electronic Excitations cannot be directly observed, their coupling to the E2g phonon leads to pronounced oscillations of the phonon feature observed through Raman scattering experiments with multiple periods and amplitudes determined by the electronic Excitation Spectrum. Such experiment and analysis has been performed up to 28 T on an exfoliated four-layer graphene specimen deposited on SiO2, and the observed oscillations correspond to the specific AB stacked four-layer graphene electronic Excitation Spectrum.
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probing the band structure of quadri layer graphene with magneto phonon resonance
arXiv: Mesoscale and Nanoscale Physics, 2012Co-Authors: C Faugeras, P Kossacki, A A L Nicolet, M Orlita, M Potemski, Ather Mahmood, D M BaskoAbstract:We show how the magneto-phonon resonance, particularly pronounced in sp2 carbon allotropes, can be used as a tool to probe the band structure of multilayer graphene specimens. Even when electronic Excitations cannot be directly observed, their coupling to the E2g phonon leads to pronounced oscillations of the phonon feature observed through Raman scattering experiments with multiple periods and amplitudes detemined by the electronic Excitation Spectrum. Such experiment and analysis have been performed up to 28T on an exfoliated 4-layer graphene specimen deposited on SiO2, and the observed oscillations correspond to the specific AB stacked 4-layer graphene electronic Excitation Spectrum.
Nihat A Berker - One of the best experts on this subject based on the ideXlab platform.
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Excitation Spectrum gap and spin wave velocity of xxz heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic XXZ spin-1/2 Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated thoughout the entire temperature and anisotropy ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the antiferromagnetic spin-liquid spin-wave velocity and the Isinglike ferromagnetic Excitation Spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an antiferromagnetic correlation in the out-of-plane s_i^z component, at higher temperatures in the antiferromagnetic XXZ chain, dominantly at low temperatures in the ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain. We find that the converse effect also occurs in the antiferromagnetic XXZ chain: an antiferromagnetic s_i^z s_j^z interaction induces a correlation in the s_i^xy component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or XY) anisotropy; (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
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Excitation Spectrum gap and spin wave velocity of x x z heisenberg chains global renormalization group calculation
Physical Review B, 2008Co-Authors: Ozan S Sariyer, Nihat A Berker, Michael HinczewskiAbstract:The anisotropic $XXZ$ spin-$\frac{1}{2}$ Heisenberg chain is studied using renormalization-group theory. The specific heats and nearest-neighbor spin-spin correlations are calculated throughout the entire temperature and anisotropy ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global description and quantitative results. We obtain, for all anisotropies, the antiferromagnetic spin-liquid spin-wave velocity and the Ising-like ferromagnetic Excitation Spectrum gap, exhibiting the spin-wave to spinon crossover. A number of characteristics of purely quantum nature are found: The in-plane interaction ${s}_{i}^{x}{s}_{j}^{x}+{s}_{i}^{y}{s}_{j}^{y}$ induces an antiferromagnetic correlation in the out-of-plane ${s}_{i}^{z}$ component, at higher temperatures in the antiferromagnetic $XXZ$ chain, dominantly at low temperatures in the ferromagnetic $XXZ$ chain, and, in-between, at all temperatures in the $XY$ chain. We find that the converse effect also occurs in the antiferromagnetic $XXZ$ chain: an antiferromagnetic ${s}_{i}^{z}{s}_{j}^{z}$ interaction induces a correlation in the ${s}_{i}^{xy}$ component. As another purely quantum effect, (i) in the antiferromagnet, the value of the specific heat peak is insensitive to anisotropy and the temperature of the specific heat peak decreases from the isotropic (Heisenberg) with introduction of either type (Ising or $XY$) of anisotropy; and (ii) in complete contrast, in the ferromagnet, the value and temperature of the specific heat peak increase with either type of anisotropy.
P Kossacki - One of the best experts on this subject based on the ideXlab platform.
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probing the band structure of quadri layer graphene with magneto phonon resonance
New Journal of Physics, 2012Co-Authors: C Faugeras, P Kossacki, A A L Nicolet, M Orlita, M Potemski, Ather Mahmood, D M BaskoAbstract:We show how the magneto-phonon resonance, particularly pronounced in sp2 carbon allotropes, can be used as a tool to probe the band structure of multilayer graphene specimens. Even when electronic Excitations cannot be directly observed, their coupling to the E2g phonon leads to pronounced oscillations of the phonon feature observed through Raman scattering experiments with multiple periods and amplitudes determined by the electronic Excitation Spectrum. Such experiment and analysis has been performed up to 28 T on an exfoliated four-layer graphene specimen deposited on SiO2, and the observed oscillations correspond to the specific AB stacked four-layer graphene electronic Excitation Spectrum.
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probing the band structure of quadri layer graphene with magneto phonon resonance
arXiv: Mesoscale and Nanoscale Physics, 2012Co-Authors: C Faugeras, P Kossacki, A A L Nicolet, M Orlita, M Potemski, Ather Mahmood, D M BaskoAbstract:We show how the magneto-phonon resonance, particularly pronounced in sp2 carbon allotropes, can be used as a tool to probe the band structure of multilayer graphene specimens. Even when electronic Excitations cannot be directly observed, their coupling to the E2g phonon leads to pronounced oscillations of the phonon feature observed through Raman scattering experiments with multiple periods and amplitudes detemined by the electronic Excitation Spectrum. Such experiment and analysis have been performed up to 28T on an exfoliated 4-layer graphene specimen deposited on SiO2, and the observed oscillations correspond to the specific AB stacked 4-layer graphene electronic Excitation Spectrum.
