• We report on an anomalous mode distinct from both optical and acoustic modes in phonon dispersion curves of bulk Si1-xGex alloy with x taking the values of 0.16, 0.32, 0.45, and 0.72. (elsevierpure.com)
  • The phonon modes were recorded over the entire surface Brillouin zone and compared with the theoretical phonon dispersion curves derived on the basis of semiempirical total-energy scheme calculated by Sandfort [Phys. (elsevierpure.com)
  • The present results of the observation fairly agree with the theoretical curves, except a discrepancy for B3 and R1 branches exhibiting a sizable dispersion between 35 and 55 meV, which was predicted to have no dispersion by the theory. (elsevierpure.com)
  • An analysis of the phonon dispersion curves of lead hafnate in the cubic phase using lattice-dynamical models. (spbstu.ru)
  • We have analyzed the phonon dispersion curves in the paraelectric phase of a lead hafnate crystal (PbHfO3) by means of two different lattice-dynamical models. (spbstu.ru)
  • The shell model allows simultaneous description of the phonon dispersion curves and the correct value of the dielectric constant. (spbstu.ru)
  • Our results on NBT suggest an anti-crossing type coupling of the TA and TO branches in the dispersion curves. (aps.org)
  • An excellent agreement has been obtained between theory and experiment for their phonon dispersion curves and Debye temperature variations. (ias.ac.in)
  • We further show that the relatively high Grüneisen parameters (1.5, 1.65, and 1.29, respectively for Si 46 -I, Si 136 -II, Si 46 -VIII), the existence of negative regions in the thermal expansion coefficient curves and very low thermal conductivities all indicate that the phonon anharmonicity in these silicon clathrates is high. (springer.com)
  • The theory is used to compute the phonon dispersion curves, frequency spectra and the lattice specific heat of \gamma-iron. (tubitak.gov.tr)
  • This allowed us to obtain a detailed experimental phonon dispersion relation for many points in the Brillouin zone. (canada.ca)
  • Transverse acoustic and transverse optic phonon modes were mapped out in these two Brillouin zones. (aps.org)
  • Scattering of photons by phonons, or Brillouin scattering, enables manipulation and control of light and has led to revolutionary applications, from slow light to saser and cooling of micromechanical resonators. (lu.se)
  • Our results enable the design of a photonic crystal with separately tailored photon and phonon dispersion for Brillouin scattering. (lu.se)
  • The dynamical matrices are used to calculate the interatomic force constants that are then used to calculate the dynamical matrices and hence the phonon frequencies along a path in the Brillouin zone and on a much thicker mesh of q points. (sissa.it)
  • Raman spectra exhibiting interface phonons in ZnSe/BeTe Superlattices (Reshina et al. (iup.edu)
  • We use density functional theory to calculate the electronic band structures, cohesive energies, phonon dispersions, and optical absorption spectra of two-dimensional In2X2 crystals, where X is S, Se, or Te. (lancs.ac.uk)
  • For the polaron in the weak and intermediate electron-phonon coupling regimes, we analyze the influence of phonon dispersion relations on the spectra. (arxiv.org)
  • For the bipolaron with weak and intermediate coupling strengths and a flat phonon band, we obtain two very different spectra. (arxiv.org)
  • In contrast to the acoustic and optical phonon modes, the energy of the anomalous mode shows no Ge fraction dependence. (elsevierpure.com)
  • We demonstrate the forward and backward scattering, by acoustic phonons in the nanowires, of (1) such optical array modes and (2) guided modes of the constituent nanowires. (lu.se)
  • One consequence of strong quadrupolar effects is the possible coupling of magnetic and lattice degrees of freedom, and it has previously been shown that a hybrid magnetoelastic mode with both magnetic and phononic character is formed in Tb2Ti2O7 by the interaction of a crystal field excitation with a transverse-acoustic phonon. (cea.fr)
  • The surface phonon dispersion was investigated by high-resolution electron-energy-loss spectroscopy on the deuterium-terminated Si (111) - (1×1) prepared by an improved wet chemical method. (elsevierpure.com)
  • The Si-D vibrations with energies between 35 and 65 meV strongly intermix with bulk phonons, and below 35 meV, the Si-D's move together in phase and the surface phonons are the same as those of hydrogen-terminated Si (111) - (1×1). (elsevierpure.com)
  • At such small distances, dispersion forces dominate over optical forces and can lead to adsorption of atoms on the surface of the photonic structure. (mpg.de)
  • We have recently explored the possibility of performing spectroscopy of the motional states of atoms bound directly to the surface of a nanofiber through dispersion and optical forces [2]. (mpg.de)
  • Surface phonon dispersion on hydrogen-terminated Si(110)-(1 × 1) surfaces studied by first-principles calculations. (bvsalud.org)
  • For example, Fermi surface, quasiparticle dispersion, and density of states or spectral function are among those. (lu.se)
  • NBT exhibits the relaxor ferroelectric behavior (strong frequency dispersion of the dielectric constant) between 850K and 600K. (aps.org)
  • freqmin_input : minimum frequency for phonon dos plot. (sissa.it)
  • Default: real determined from phonon frequencies freqmax_input : maximum frequency for phonon dos plot. (sissa.it)
  • The latter also has a temperature-dependent resonance at a frequency below the phonon frequency. (arxiv.org)
  • In such a system, the phonon dispersion can be tuned by varying the geometry of the constituent nanowires. (lu.se)
  • In contrast, the placement of the nanowires in the photonic crystal can be used for tuning optical array modes, without altering the phonon dispersion. (lu.se)
  • The force constants and the crystal structure of α-Fe were used to estimate the phonon dispersion relations, phonon density of states, and specific heat by computer simulation. (batan.go.id)
  • The code uses the phonon frequencies calculated on the thick mesh of q points to get the phonon density of states using a smearing approach. (sissa.it)
  • Default: character(len=*) 'matdyn.modes' fldosfrq : file where the frequencies used to calculate the phonon density of states are saved. (sissa.it)
  • Our simulations of anharmonic phonon renormalization go beyond low-order perturbation theory and capture these striking effects, showing that the large phonon shifts directly affect the thermal conductivity by altering both the phonon scattering phase space and the group velocities. (ornl.gov)
  • These results provide a detailed microscopic understanding of phase stability and thermal transport in technologically important materials, providing further insights on ways to control phonon propagation in thermoelectrics, photovoltaics, and other materials requiring thermal management. (ornl.gov)
  • We apply quasi-harmonic approximation to study structural stability, the possibility of temperature or pressure-driven phase transitions, along with Grüneisen parameters, coefficients of thermal expansion and thermal conductivities to estimate the degree of phonon anharmonicity for selected silicon clathrates. (springer.com)
  • the thermal properties are calculated from the phonon dos. (sissa.it)
  • the thermal properties are calculated from the direct integration using the phonon frequencies. (sissa.it)
  • She revealed that electron-phonon coupling increases for smaller chiral angles. (wikipedia.org)
  • The experimental verification of chiral phonons (bosons) remains challenging, however, despite their expected strong impact on fundamental physical properties. (psi.ch)
  • A comprehensive picture of polaron and bipolaron physics is essential to understand the optical absorption spectrum in many materials with electron-phonon interactions. (arxiv.org)
  • The suface-projected bulk phonon is distributed below 65 meV of the vibration energy, and the Si-D modes with higher energies than that are independent of SPBP. (elsevierpure.com)
  • In fact, first-principles phonon-dispersion calculations show that the high-symmetry reference structures of many complex oxides have entire ranges of instabilities that do not contribute to the bulk ground state structure. (aps.org)
  • Labbé and Bok [ 5 ] proposed the Van Hove scenario for the cuprates, using electron-phonon interaction and predicted an anomalous isotope effect. (hindawi.com)
  • The combination of this source with Scienta Omicron high resolution ARPES analysers creates a platform for vibrational spectroscopy and phonon dispersion measurements. (scientaomicron.com)
  • However, the design of the waveguide geometry tunes and alters the phonon and photon dispersion simultaneously. (lu.se)
  • We find that the motional decoherence due to waveguide phonons and the resulting broadening of motional resonances is significant. (mpg.de)
  • The obtained force constants among first-nearest-neighboring atoms is 2.3 eV/Å 2 at 295 K and the specific heat is 185 meV/K at 150 K. The calculated phonon dispersion relations and specific heat of α-Fe are similar to those obtained from inelastic neutron scattering and specific heat measurements, respectively. (batan.go.id)
  • The phonon dispersion relations for cubic PbTiO$_3$ ($T_c=$763 K) have been determined along the high symmetry directions at $T=$793 K using inelastic neutron scattering. (aps.org)
  • With this option the code makes a self-consistent calculation followed by a phonon dispersion calculation at a fixed geometry. (sissa.it)
  • Default: determined from previous data nq1_d, nq2_d, nq3_d : thick mesh for phonon dos calculation. (sissa.it)
  • Default: integer 192, 192, 192 phdos_sigma : the smearing used for phonon dos calculation (in cm^-1). (sissa.it)
  • X=S, Se, Te) are scaled to the thickness of one three-atom-thick layer, the electronic dispersion undergoes a transition from an indirect to a direct band gap due to quantum confinement effects. (uconn.edu)
  • Wu, Wei, "Phonon Dispersion and Band Gap Engineering of Strained and Isotopically Enriched Atomically Thin Transition Metal Dichalcogenide Semiconductors" (2018). (uconn.edu)
  • Although the phonon softening occurs simultaneously, the softening of the zone center TO mode plays an important role in the single phase transition. (aps.org)
  • Theoretical calculations of interface phonons (unpublished) providing excellent corroboration to the Raman scattering data of Reshina et al. (iup.edu)
  • From this information, we extract the optical conductivity for the Holstein polaron and bipolaron with dispersive phonons at finite temperatures. (arxiv.org)
  • Quite recently, Raman scattering in ZnSe/BeTe superlattices (which share no-common cations or anions in the interfaces) are studied - observing Kliewer-Fuchs-type electrostatic interface phonons (see Fig. 2). (iup.edu)
  • We find that these materials are indirect-band-gap semiconductors with a sombrero-shaped dispersion of holes near the valence-band edge. (lancs.ac.uk)
  • We identify two crystalline phases (alpha and beta) of monolayers of hexagonal In2X2, and show that they are characterized by different sets of Raman-active phonon modes. (lancs.ac.uk)
  • The phonon dispersion relations of the anomalous mode indicate that there was no momentum dependence, similar to those of the longitudinal and transverse optical modes (Ge-Ge, Si-Ge, and Si-Si modes). (elsevierpure.com)
  • Now an international collaboration of researchers has shown that dispersion- and diffraction-free propagation is possible, with a resolution that beats the diffraction limit by more than an order of magnitude, in twisted layers of 2D molybdenum trioxide. (physicsworld.com)
  • We also examine the dispersion relations of the exciton branches that develop from the crystal field excitation in the same temperature regime that the coupled mode appears, and find three quasidispersionless branches where four are expected, each with a distinctive structure factor indicating that they are nonetheless cooperative excitations. (cea.fr)
  • The latter phenomenon has been well studied in other perovskite systems such as KTaO$_{3}$ where a pronounced kink is observed in the dispersion curve of the TA and TO branches at a critical q value. (aps.org)
  • We interpret the overall structure of the spectrum as containing four branches, one hybridized with the phonons and gaining a strong dispersion, and three remaining dispersionless. (cea.fr)
  • Single-defect phonons imaged by electron microscopy. (nature.com)
  • The strong correlations are surely very important in the underdoped regime but we shall show that electron-phonon interaction coupled with the Van Hove scenario may explain must of the properties in the region of optimum doping and the overdoped region. (hindawi.com)
  • For strong electron-phonon coupling, the known result of an asymmetric Gaussian is reproduced for a flat phonon band. (arxiv.org)
  • Furthermore, our results reveal an enhanced interaction of array modes with phonons that we attribute to the specific scattering mechanism. (lu.se)
  • However, a sufficient reduction of the phonon-induced decoherence is within reach and should result in a clearly quantized motional spectrum. (mpg.de)
  • However, the mechanisms of tuning electronic band gap energy and phonon dispersion are still unclear. (uconn.edu)
  • For a finite phonon bandwidth, the center of the Gaussian is either shifted to larger or smaller frequencies, depending on the sign of the phonon hopping. (arxiv.org)