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Density functional perturbation theory calculations of alpha-quartz using extended norm conserving pseudopotentials have been used to study the elastic properties and phonon dispersion relations along various high symmetry directions as a…

Materials Science · Physics 2007-05-23 N. Choudhury , S. L. Chaplot

We study the impact of structural variations (that is slowly varying geometry aberrations and internal strain fields) on the width and shape of the stimulated Brillouin scattering (SBS) resonance in nanoscale waveguides. We find that they…

Phosphorene, an emerging elemental two-dimensional (2D) direct band gap semiconductor with fascinating structural and electronic properties distinctively different from other 2D materials such as graphene and MoS2, is promising for novel…

Materials Science · Physics 2015-04-21 Yongqing Cai , Qingqing Ke , Gang Zhang , Yuan Ping Feng , Vivek B Shenoy , Yong-Wei Zhang

Microstrip ferromagnetic resonance and Brillouin scattering are used to provide a comparative determination of the magnetic parameters of thin permalloy layers interfaced with a non-magnetic (Al2O3) or with an antiferromagnetic oxide (NiO).…

The temperature dependence below $T_{c}$ of the lineshape of optical phonons of different symmetry as seen in Raman scattering is investigated for superconductors with anisotropic energy gaps. It is shown that the symmetry of the…

Condensed Matter · Physics 2009-10-22 T. P. Devereaux

A 20-band sp3d5s* spin-orbit-coupled, semi-empirical, atomistic tight-binding model is used with a semi-classical, ballistic, field-effect-transistor (FET) model, to examine the ON-current variations to size variations of [110] oriented…

Mesoscale and Nanoscale Physics · Physics 2009-01-30 Neophytos Neophytou , Gerhard Klimeck

All phonons in a single crystal of NaBr were measured by inelastic neutron scattering at temperatures of 10, 300 and 700 K. Even at 300 K the phonons, especially the longitudinal-optical (LO) phonons, showed large shifts in frequencies, and…

Materials Science · Physics 2020-08-26 Y. Shen , C. N. Saunders , C. M. Bernal , D. L. Abernathy , M. E. Manley , B. Fultz

Anomalous thermal expansion behaviour of several open frame-work compounds has been extensively investigated using the techniques of inelastic neutron scattering and lattice dynamics. These compounds involve increasing level of structural…

Materials Science · Physics 2017-11-21 R. Mittal , M. K. Gupta , S. L. Chaplot

A crack free and high structural quality Sr2Nb2O7 single crystals were grown by the optical float zone method using optimized growth parameters. Laue pattern confirms single crystalline nature of the grown crystal. Temperature dependent…

Anharmonic effects in an atomic monolayer thin crystal with honeycomb lattice structure are investigated by analytical and numerical lattice dynamical methods. Starting from a semi-empirical model for anharmonic couplings of third and…

Materials Science · Physics 2015-05-20 K. H. Michel , S. Costamagna , F. M. Peeters

Ever increasing demand of skyrmion manipulation in nanodevices has brought up interesting research to 8 understand the stabilization of these topologically protected chiral structures. To understand the actual shape 9 and size of skyrmion…

Mesoscale and Nanoscale Physics · Physics 2020-03-30 Gajanan Pradhan , Subhankar Bedanta

In plasmonics, nonlocal effects arise when the material response to optical excitations is strongly dependent on the spatial correlations of the excitation. It is well known that a classical free electron gas system supports local Drude…

The impact of dispersion relations, anisotropy, and Brillouin zone structure on intrinsic phonon scattering rates has been assessed within the harmonic approximation-perturbation theory approach for lattice dynamics. Anisotropic nonlinear…

Materials Science · Physics 2022-06-15 Ahmed Hamed , Anter El-Azab

The thermal conductivity of a freestanding single-crystal silicon membrane may be reduced significantly by attaching nanoscale pillars on one or both surfaces. Atomic resonances of the nanopillars locally and intrinsically couple with the…

Mesoscale and Nanoscale Physics · Physics 2021-09-01 Hossein Honarvar , Mahmoud I. Hussein

Experimental phonon imaging in diamond anvils cell is demonstrated to be an adequate tool to extract the complete set of elastic constants of single-crystalline silicon up to the ZB$\rightarrow \beta-$Sn transition (10 GPa). Contrary to…

Materials Science · Physics 2015-05-19 F. Decremps , L. Belliard , M. Gauthier , B. Perrin

The effect of geometrical confinement, atomic position and orientation of Silicon nanowires (SiNWs) on their thermal properties are investigated using the phonon dispersion obtained using a Modified Valence Force Field (MVFF) model. The…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Abhijeet Paul , Mathieu Luisier , Gerhard Klimeck

The morphology of nanoscopic Ag grains significantly affects the phonons. Atomistic simulations show that realistic nanograin models display complex vibrational properties. (1) Single-crystalline grains. Nearly-pure torsional and radial…

Materials Science · Physics 2007-05-23 Gustavo A. Narvaez , Jeongnim Kim , John W. Wilkins

Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad central peak (CP), and additional Brillouin doublets (BD), that can both be related to phonon-density fluctuations. On the basis of new high-resolution neutron…

Materials Science · Physics 2007-05-23 E. Farhi , A. K. Tagantsev , B. Hehlen , R. Currat , L. A. Boatner , E. Courtens

Nanostructured semiconducting materials are promising candidates for thermoelectrics due to their potential to suppress phonon transport while preserving electrical properties. Modeling phonon-boundary scattering in complex geometries is…

Materials Science · Physics 2017-10-02 Giuseppe Romano , Alexie M. Kolpak

Vibrational optical spectroscopies can be enhanced by surface plasmons to reach molecular-sized limits of detection and characterization. The level of enhancement strongly depends on microscopic details of the sample that are generally…