PRB: Dynamics, dynamical systems, lattice effects, quantum solids

Homogenization of acoustic metamaterials of Helmholtz resonators in fluid

Xinhua Hu, Kai-Ming Ho, C. T. Chan, and Jian Zi — 2008-05-01T00:00:00-04:00

Author(s): Xinhua Hu, Kai-Ming Ho, C. T. Chan, and Jian Zi
By using a two-step homogenization approach, we derive analytical formulas of effective mass density ρ_{e} and effective bulk modulus B_{e} for two- and three-dimensional acoustic metamaterials of Helmholtz resonators (HRs) in fluid. A negative B_{e} is found at certain frequencies due to the monop...
[Phys. Rev. B 77, 172301] Published Thu May 01, 2008

Optically induced lattice dynamics probed with ultrafast x-ray diffraction

2008-04-29T00:00:00-04:00

Author(s): H. J. Lee, J. Workman, J. S. Wark, R. D. Averitt, A. J. Taylor, J. Roberts, Q. McCulloch, D. E. Hof, N. Hur, S.-W. Cheong, and D. J. Funk
We have studied the picosecond lattice dynamics of optically pumped hexagonal LuMnO_{3} by using ultrafast x-ray diffraction. The results show a shift and broadening of the diffraction curve due to the stimulated lattice expansion. To understand the transient response of the lattice, the measured ti...
[Phys. Rev. B 77, 132301] Published Tue Apr 29, 2008

Depolarization current density within the symmetric double-well potential model for solid ionic conductors

S. N. Taraskin and F. Henn — 2008-04-28T00:00:00-04:00

Author(s): S. N. Taraskin and F. Henn
An approximate analytic expression for the depolarization current density has been derived within the symmetric double-well potential model. How to relate the depolarization current density response measured under iso- or nonisothermal conditions with the distribution of energy barriers has been dem...
[Phys. Rev. B 77, 134306] Published Mon Apr 28, 2008

Temperature-dependent diffusion coefficients from ab initio computations: Hydrogen, deuterium, and tritium in nickel

2008-04-11T00:00:00-04:00

Author(s): Erich Wimmer, Walter Wolf, Jürgen Sticht, Paul Saxe, Clint B. Geller, Reza Najafabadi, and George A. Young
The temperature-dependent diffusion coefficients of interstitial hydrogen, deuterium, and tritium in nickel are computed using transition state theory. The coefficient of thermal expansion, the enthalpy and entropy of activation, and the pre-exponential factor of the diffusion coefficient are obtain...
[Phys. Rev. B 77, 134305] Published Fri Apr 11, 2008

Observations outside the light cone: Algorithms for nonequilibrium and thermal states

M. B. Hastings — 2008-04-09T00:00:00-04:00

Author(s): M. B. Hastings
We apply algorithms based on Lieb-Robinson bounds to simulate time-dependent and thermal quantities in quantum systems. For time-dependent systems, we modify a previous mapping to quantum circuits to significantly reduce the computer resources required. This modification is based on a principle of â...

[Phys. Rev. B 77, 144302] Published Wed Apr 09, 2008

Faraday effect in a short pulse propagating in a resonant medium under an ultra-strong magnetic field

J. G. Huang (黄俊刚), G. Slavcheva, and O. Hess — 2008-04-08T00:00:00-04:00

Author(s): J. G. Huang (黄俊刚), G. Slavcheva, and O. Hess
We propose a dynamical model for description of the nonlinear Faraday rotation experienced by a short pulse propagating in a resonant medium subject to an ultra-strong static magnetic field. Under the assumptions of a sufficiently strong external magnetic field, such that the Zeeman splitting of the...
[Phys. Rev. B 77, 134304] Published Tue Apr 08, 2008

Lattice dynamics of skutterudites: Inelastic x-ray scattering on CoSb_{3}

M. Rotter, P. Rogl, A. Grytsiv, W. Wolf, M. Krisch, and A. Mirone — 2008-04-04T00:00:00-04:00

Author(s): M. Rotter, P. Rogl, A. Grytsiv, W. Wolf, M. Krisch, and A. Mirone
Skutterudite based materials are important for thermoelectric applications. In order to be able to tune the thermoelectric properties, it is necessary to understand the mechanism of thermal conductivity, which, in turn, is strongly influenced by the lattice dynamics. The lattice dynamics of the skut...
[Phys. Rev. B 77, 144301] Published Fri Apr 04, 2008

Infrared properties of ferropericlase Mg_{1−x} Fe_{x} O : Experiment and theory

2008-04-04T00:00:00-04:00

Author(s): Tao Sun, Philip B. Allen, David G. Stahnke, Steven D. Jacobsen, and Christopher C. Homes
The temperature dependence of the reflectance spectra of magnesium oxide (MgO) and ferropericlase ( Mg_{1−x} Fe_{x} O , for x=0.06 and x=0.27 ) have been measured over a wide frequency range ( ≈50−32 000 cm^{−1} ) at 295 and 6 K. The complex dielectric function has been determined from a...
[Phys. Rev. B 77, 134303] Published Fri Apr 04, 2008

Identification of a stable phase for the high-capacity hydrogen-storage material Zn(BH_{4} )_{2} from density functional theory and lattice dynamics

Pabitra Choudhury, Venkat R. Bhethanabotla, and Elias Stefanakos — 2008-04-03T00:00:00-04:00

Author(s): Pabitra Choudhury, Venkat R. Bhethanabotla, and Elias Stefanakos
First-principles calculations were performed on Zn(BH_{4} )_{2} using density functional theory (DFT) within the local density approximation and the projected augmented wave method. Zn(BH_{4} )_{2} is a promising candidate for hydrogen storage with a capacity of 8.5 wt % . A direct method lattice ...
[Phys. Rev. B 77, 134302] Published Thu Apr 03, 2008

Self-assembly of neon into a quantum gel with crystalline structure in superfluid ^{4} He : Prediction from density functional theory

Jussi Eloranta — 2008-04-02T00:00:00-04:00

Author(s): Jussi Eloranta
Doping superfluid ^{4} He with a low concentration of neon atoms is predicted to lead to the self-assembly of “quantum gel” with crystalline structure, where each atom is isolated by a mixture of liquid and solid helium. The formation of this structure is shown to originate from the repulsive or...
[Phys. Rev. B 77, 134301] Published Wed Apr 02, 2008

Jahn-Teller effect in the augmented Hubbard model

D. Schneider, K.-H. Höck, and P. S. Riseborough — 2008-03-28T00:00:00-04:00

Author(s): D. Schneider, K.-H. Höck, and P. S. Riseborough
We investigate the effects induced by the interplay of microscopic degrees of freedom. In many cases, one has to consider spin and orbital degeneracy to explain complex structures of magnetic and orbital order. Frequently, attention is focused on electronic correlations. We study how the interaction...
[Phys. Rev. B 77, 094306] Published Fri Mar 28, 2008

Redistribution of electronic excitation energy in impurity crystals

G. G. Demirkhanyan and R. B. Kostanyan — 2008-03-27T00:00:00-04:00

Author(s): G. G. Demirkhanyan and R. B. Kostanyan
A model which permits obtaining kinetic law for excitation decay in the presence of clusters of impurity ions of arbitrary length in a dielectric crystal matrix is proposed. The phenomenon of electronic excitation trapping in impurity paired centers (PCs) in doped dielectric crystals is investigated...
[Phys. Rev. B 77, 094305] Published Thu Mar 27, 2008

Vibrational dynamics and phonon dispersion of polycrystalline ice XII and of high-density amorphous ice

M. M. Koza, H. Schober, S. F. Parker, and J. Peters — 2008-03-27T00:00:00-04:00

Author(s): M. M. Koza, H. Schober, S. F. Parker, and J. Peters
The dynamics of high-density polycrystalline ice XII have been studied with neutron and x-ray scattering techniques in the range of translational and librational modes. Depending on the energy range of interest, different neutron spectrometers have been utilized. This way, accurate information on mo...
[Phys. Rev. B 77, 104306] Published Thu Mar 27, 2008

Line shapes of narrow optical bands: Infrared absorption by U centers and heavier impurities in alkali halides

2008-03-27T00:00:00-04:00

Author(s): Miguel Lagos, Felipe Asenjo, Roberto Hauyón, Denisse Pastén, Hernán González, Ricardo Henríquez, and Roberto Troncoso
The shape of the bands for photon absorption and emission by the local constituents of a solid is governed mainly by processes involving many low-energy acoustic phonons. This applies not only to wide bands, such as those exhibited by F centers, but also to narrow ones, as those observed for infrare...
[Phys. Rev. B 77, 104305] Published Thu Mar 27, 2008

Sonic band gaps in one-dimensional phononic crystals with a symmetric stub

2008-03-21T00:00:00-04:00

Author(s): Anne-Christine Hladky-Hennion, Jérôme Vasseur, Bahram Djafari-Rouhani, and Michel de Billy
The propagation of elastic waves through a one-dimensional chain of beads with grafted stubs is experimentally as well as numerically investigated. The results obtained by both approaches are well correlated and show that the stub introduces a dip in the spectral response of the chain, which is rela...
[Phys. Rev. B 77, 104304] Published Fri Mar 21, 2008

Surface acoustic waves in finite slabs of three-dimensional phononic crystals

R. Sainidou, B. Djafari-Rouhani, and J. O. Vasseur — 2008-03-18T00:00:00-04:00

Author(s): R. Sainidou, B. Djafari-Rouhani, and J. O. Vasseur
We study theoretically, by means of layer-multiple-scattering techniques, the propagation of elastic waves through finite slabs of phononic crystals consisting of metallic spheres in a polyester matrix, embedded in air. In particular, we focus on the study of modes localized on the surfaces of the s...
[Phys. Rev. B 77, 094304] Published Tue Mar 18, 2008

Transport in open spin chains: A Monte Carlo wave-function approach

Mathias Michel, Ortwin Hess, Hannu Wichterich, and Jochen Gemmer — 2008-03-14T00:00:00-04:00

Author(s): Mathias Michel, Ortwin Hess, Hannu Wichterich, and Jochen Gemmer
We investigate energy transport in several two-level atom or spin- 1∕2 models by a direct coupling to heat baths of different temperatures. The analysis is carried out on the basis of a recently derived quantum master equation which describes the nonequilibrium properties of internally weakly coup...
[Phys. Rev. B 77, 104303] Published Fri Mar 14, 2008

Energy radiation and limiting speeds of fast moving edge dislocations in tungsten

Zhaohui Jin, Huajian Gao, and Peter Gumbsch — 2008-03-11T00:00:00-04:00

Author(s): Zhaohui Jin, Huajian Gao, and Peter Gumbsch
The energy loss of a uniformly moving dislocation radiating lattice waves is quantitatively studied by atomistic simulations. The velocity dependence of the energy radiation provides a unique way to understand limiting behavior exhibited by fast moving dislocations. In combination with theoretical a...
[Phys. Rev. B 77, 094303] Published Tue Mar 11, 2008

O-H wag vibrations in hydrated BaIn_{x} Zr_{1−x} O_{3−x∕2} investigated with inelastic neutron scattering

2008-03-11T00:00:00-04:00

Author(s): Maths Karlsson, Aleksandar Matic, Stewart F. Parker, Istaq Ahmed, Lars Börjesson, and Sten Eriksson
The nature of O-H wag vibrations in the cubic proton conducting perovskite-type oxides, BaIn_{x} Zr_{1−x} O_{3−x∕2} (x=0.20–0.75) have been investigated by means of inelastic neutron scattering. Our spectroscopic results show that the O-H wag vibrations are manifested as a broad band between...
[Phys. Rev. B 77, 104302] Published Tue Mar 11, 2008

Acoustic phonon scattering from particles embedded in an anisotropic medium: A molecular dynamics study

Neil Zuckerman and Jennifer R. Lukes — 2008-03-05T00:00:00-05:00

Author(s): Neil Zuckerman and Jennifer R. Lukes
Acoustic phonon scattering from isolated nanometer-scale impurity particles embedded in anisotropic media is investigated using molecular dynamics simulation. The spectral-directional dependence of the scattering, for both longitudinal and transverse modes, is found through calculation of scattering...
[Phys. Rev. B 77, 094302] Published Wed Mar 05, 2008

Hindered rotation of HArF in solid argon: Infrared spectroscopy and a theoretical model

2008-03-05T00:00:00-05:00

Author(s): Anastasia V. Bochenkova, Leonid Khriachtchev, Antti Lignell, Markku Räsänen, Hanna Lignell, Alexander A. Granovsky, and Alexander V. Nemukhin
Infrared spectroscopy results on the argon compound HArF in solid argon give evidence of its hindered rotation (libration). Experimental studies emphasize the thermal modification of the IR absorption bands, in particular in the region of the previously unassigned 1992cm^{−1} absorption band. The ...
[Phys. Rev. B 77, 094301] Published Wed Mar 05, 2008

^{6} Li and ^{7} Li NMR line-shape and stimulated-echo studies of lithium ionic hopping in LiPO_{3} glass

Sandra Faske, Hellmut Eckert, and Michael Vogel — 2008-03-03T00:00:00-05:00

Author(s): Sandra Faske, Hellmut Eckert, and Michael Vogel
^{6} Li and ^{7} Li NMRs are used to investigate the lithium ion dynamics in LiPO_{3} glass. In particular, ^{6} Li NMR stimulated-echo experiments are used to provide straightforward access to two-time correlation functions characterizing the lithium ionic hopping motion in the millisecond regime i...
[Phys. Rev. B 77, 104301] Published Mon Mar 03, 2008

Raman scattering in KOs_{2} O_{6}

2008-02-26T00:00:00-05:00

Author(s): Takumi Hasegawa, Yuichi Takasu, Norio Ogita, Masayuki Udagawa, Jun-Ichi Yamaura, Yohei Nagao, and Zenji Hiroi
KOs_{2} O_{6} with a β -pyrochlore structure undergoes a superconducting transition at T_{c} =9.6K , which is the highest temperature among a series of compounds, AOs_{2} O_{6} ( A=K , Rb, and Cs). In this structure, it is expected that vibrations of the atoms have a large amplitude and a large anh...
[Phys. Rev. B 77, 064303] Published Tue Feb 26, 2008

Specific heat of Sb: Isotopic and spin-orbit effects from measurements and ab initio calculations

2008-02-25T00:00:00-05:00

Author(s): J. Serrano, R. K. Kremer, M. Cardona, G. Siegle, L. E. Díaz-Sánchez, and A. H. Romero
We report measurements of the specific heat C of antimony crystals in the 2–50K temperature range for several isotopic compositions and ab initio calculations of the specific heat as a function of temperature. The contribution of spin-orbit interaction and the dependence of C on isotopic mass are ...
[Phys. Rev. B 77, 054303] Published Mon Feb 25, 2008

Intrinsically localized mode in α-U as a precursor to a solid-state phase transition

Michael E. Manley, Jeffrey W. Lynn, Ying Chen, and Gerard H. Lander — 2008-02-19T00:00:00-05:00

Author(s): Michael E. Manley, Jeffrey W. Lynn, Ying Chen, and Gerard H. Lander
The high-temperature behavior of an intrinsically localized mode (ILM) in α-U was measured using inelastic neutron scattering. The mode, which forms above 450K on the [010] boundary, becomes undetectable at 675K . Thermodynamic and transport anomalies that develop with the ILM persist to temperatur...
[Phys. Rev. B 77, 052301] Published Tue Feb 19, 2008

Autocorrelations and thermal fragility of anyonic loops in topologically quantum ordered systems

Zohar Nussinov and Gerardo Ortiz — 2008-02-14T00:00:00-05:00

Author(s): Zohar Nussinov and Gerardo Ortiz
Are systems that display topological quantum order (TQO), and have a gap to excitations, hardware fault-tolerant at finite temperatures? We show that in models that display low d -dimensional gaugelike symmetries, such as Kitaev’s and its generalizations, the expectation value of topological symme...
[Phys. Rev. B 77, 064302] Published Thu Feb 14, 2008

Phonon dispersions of hydrogenated and dehydrogenated carbon nanoribbons

Megumi Yamada, Yoshihiro Yamakita, and Koichi Ohno — 2008-02-13T00:00:00-05:00

Author(s): Megumi Yamada, Yoshihiro Yamakita, and Koichi Ohno
Phonon dispersion relations are presented for carbon nanoribbons along multirow structures of hexagonal rings with zigzag and armchair edges. The dispersions are compared with the ΓK and ΓM dispersions of graphite as a function of ribbon width m . The force constants are obtained from zone folding...
[Phys. Rev. B 77, 054302] Published Wed Feb 13, 2008

Surface instability and isotopic impurities in quantum solids

E. Cappelluti, G. Rastelli, S. Gaudio, and L. Pietronero — 2008-02-07T00:00:00-05:00

Author(s): E. Cappelluti, G. Rastelli, S. Gaudio, and L. Pietronero
In this paper, we employ a self-consistent harmonic approximation to investigate surface melting and local melting close to quantum impurities in quantum solids. We show that surface melting can occur at temperatures much lower than the critical temperature T_{c} of the solid phase instability in th...
[Phys. Rev. B 77, 054301] Published Thu Feb 07, 2008

Atomic form-factor measurements in the low-momentum transfer region for Li, Be, and Al by inelastic x-ray scattering

2008-02-01T00:00:00-05:00

Author(s): A. Alatas, A. H. Said, H. Sinn, G. Bortel, M. Y. Hu, J. Zhao, C. A. Burns, E. Burkel, and E. E. Alp
We report measurements of the atomic form factor of lithium, beryllium, and aluminum single crystals at low-momentum transfers (Q=1.6–50nm^{−1} ) from the intensity of phonons observed by inelastic x-ray scattering. Comparing to Hartree-Fock calculations, the form factor deviates significantly i...
[Phys. Rev. B 77, 064301] Published Fri Feb 01, 2008

Li jump process in h-Li_{0.7} TiS_{2} studied by two-time ^{7} Li spin-alignment echo NMR and comparison with results on two-dimensional diffusion from nuclear magnetic relaxation

M. Wilkening and P. Heitjans — 2008-01-31T00:00:00-05:00

Author(s): M. Wilkening and P. Heitjans
^{7} Li spin-alignment NMR is used to trace ultraslow diffusion of Li^{+} in the layered Li conductor Li_{x} TiS_{2} (x=0.7) . Two-time correlation functions were recorded for fixed evolution times as a function of mixing time at temperatures within the ^{7} Li rigid-lattice regime. The correspondin...
[Phys. Rev. B 77, 024311] Published Thu Jan 31, 2008