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We report the adiabatic elastic constants of single-crystal thorium dioxide over a temperature range of 77 - 350 K. Time-domain Brillouin scattering (TDBS), an all-optical, non-contact picosecond ultrasonic technique, is used to generate…

Phonon dispersions in <100> silicon nanowires (SiNW) are modeled using a Modified Valence Force Field (MVFF) method based on atomistic force constants. The model replicates the bulk Si phonon dispersion very well. In SiNWs, apart from four…

Mesoscale and Nanoscale Physics · Physics 2015-03-17 Abhijeet Paul , Mathieu Luisier , Gerhard Klimeck

We present a study of thermal conductivity, $\kappa$, in undoped and doped strontium titanate in a wide temperature range (2-400 K) and detecting different regimes of heat flow. In undoped SrTiO$_{3}$, $\kappa$ evolves faster than cubic…

We compute both electron- and phonon transmissions in thin disordered silicon nanowires. Our atomistic approach is based on tight-binding and empirical potential descriptions of the electronic and phononic systems, respectively. Surface…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Troels Markussen , Antti-Pekka Jauho , Mads Brandbyge

We perform thermodynamic and inelastic neutron scattering (INS) measurements to study the lattice dynamics (phonons) of a cubic collinear antiferromagnet Cu$_3$TeO$_6$ which hosts topological spin excitations (magnons). While the specific…

We investigate the temperature dependence of the frequency and linewidth of the triply-degenerate T$_{2g}$ zone-centered optical phonon in flux-grown ceria and hydrothermally-synthesized thoria single crystals from room temperature to 1273…

Phonon modes found in low frequency Raman scattering from $CdS_{1-x}Se_x$ nanocrystals embedded in borosilicate glass arising from confined acoustic phonons are investigated. In addition to the breathing modes and quadrupolar modes, two…

Materials Science · Physics 2008-03-10 Sanjeev K. Gupta , Satyaprakash Sahoo , Prafulla K. Jha , A. K. Arora , Y. M. Azhniuk

The thermalization of hot carriers and phonons gives direct insight into the scattering processes that mediate electrical and thermal transport. Obtaining the scattering rates for both hot carriers and phonons currently requires multiple…

We have grown intermetallic ErPd$_2$Si$_2$ single crystals employing laser-diodes with the floating-zone method. The temperature-dependent crystallography was determined using synchrotron and in-house X-ray powder diffraction measurements…

Materials Science · Physics 2022-08-02 Kaitong Sun , Yinghao Zhu , Si Wu , Junchao Xia , Pengfei Zhou , Qian Zhao , Chongde Cao , Hai-Feng Li

High quality single crystals of Bi2Se3 were grown using a modified Bridgman technique, the detailed study were carried out using Raman spectroscopy and characterized by Laue diffraction and high resolution transmission electron microscopy.…

The confinement of high frequency phonons approaching 1 GHz is demonstrated in phonon-trapping acoustic cavities at cryogenic temperatures using a low-coupled network approach. The frequency range is extended by nearly an order of…

Mesoscale and Nanoscale Physics · Physics 2013-09-20 M. Goryachev , D. L. Creedon , S. Galliou , M. E. Tobar

First-principles calculations are employed to investigate the phonon transport of BiCuOSe. Our calculations reproduce the lattice thermal conductivity of BiCuOSe. The calculated gruneisen parameter is 2.4~2.6 at room temperature, a fairly…

Materials Science · Physics 2016-03-10 Hezhu Shao , Xiaojian Tan , Guo-Qiang Liu , Jun Jiang , Haochuan Jiang

We report measurements of the neutron diffuse scattering in a single crystal of the relaxor ferroelectric material 95.5%Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 (PZN-4.5%PT). We show that the diffuse scattering at high temperatures has a quasielastic…

Materials Science · Physics 2013-01-10 Zhijun Xu , Jinsheng Wen , E. Mamontov , C. Stock , P. M. Gehring , Guangyong Xu

Non-Fourier thermal transports have drawn significant attention for decades. Among them, the frequency dependent thermal conductivity has been extensively explored by pump-probe techniques, such as time-domain thermoreflectance, which is…

Materials Science · Physics 2024-12-04 Yizhe Liu , Qinshu Li , Fang Liu , Xinqiang Wang , Bo Sun

With a terahertz time-domain spectrometer (0.3 - 3.0 THz) we have measured the optical conductivity of the type-I clathrate Ba$_8$Ga$_{16}$Sn$_{30}$ at temperatures from 300 K down to 7 K. Independent six spectra superimposed on the Drude…

Materials Science · Physics 2010-07-27 T. Mori , K. Iwamoto , S. Kushibiki , H. Honda , H. Matsumoto , N. Toyota , K. Suekuni , M. A. Avila , T. Takabatake

The role of doping in tailoring thermal transport in semiconductors is critical for efficient thermal management in electronic devices. While the effects of doping have been extensively studied to tune electrical properties, its impact on…

Materials Science · Physics 2025-04-30 Zifeng Huang , Jianbo Liang , Yuxiang Wang , Zixuan Sun , Naoteru Shigekawa , Ming Li , Runsheng Wang , Zhe Cheng

The spherically averaged structure function $\soq$ obtained from pulsed neutron powder diffraction contains both elastic and inelastic scattering via an integral over energy. The Fourier transformation of $\soq$ to real space, as is done in…

Materials Science · Physics 2016-08-31 D. A. Dimitrov , D. Louca , H. Röder

We report plane-polarized Raman scattering spectra of iron oxypnictide superconductor NdFeAsO$_{1-x}$F$_x$ single crystals with varying fluorine $x$ content. The spectra exhibit sharp and symmetrical phonon lines with a weak dependence on…

Superconductivity · Physics 2009-11-13 Y. Gallais , A. Sacuto , M. Cazayous , P. Cheng , L. Fang , H. H. Wen

Using a microscopic model of lattice vibrations in the STO(001) substrate, an additional 50 mev longitudinal optical (LO) interface mode is identified. The soft mode propagating mainly in the first TiO2 layer ("O chains") has stronger…

Superconductivity · Physics 2019-08-28 Baruch Rosenstein , B. Ya. Shapiro

We present the results of a neutron scattering study of the high energy phonons in the superconducting graphite intercalation compound CaC$_6$. The study was designed to address hitherto unexplored aspects of the lattice dynamics in…

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