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Reflection and transmission as a function of temperature (5--300 K) have been measured on single crystals of the multiferroic compound FeTe$_{2}$O$_{5}$Br utilizing light spanning the far infrared to the visible portions of the…

Strongly Correlated Electrons · Physics 2015-06-12 K. H. Miller , X. S. Xu , H. Berger , V. Craciun , X. Xi , C. Martin , G. L. Carr , D. B. Tanner

We have integrated density functional theory (DFT) into quantitative convergent-beam electron diffraction (QCBED) to create a synergy between experiment and theory called QCBED-DFT. This synergy resides entirely in the electron density…

Strongly Correlated Electrons · Physics 2021-05-05 Ding Peng , Philip N. H. Nakashima

A comprehensive picture of polaron and bipolaron physics is essential to understand the optical absorption spectrum in many materials with electron-phonon interactions. In particular, the finite-temperature properties are of interest since…

Strongly Correlated Electrons · Physics 2022-10-27 David Jansen , Janez Bonča , Fabian Heidrich-Meisner

The effective electron mass parameter in Si-doped Al$_{0.72}$Ga$_{0.28}$N is determined to be $m^\ast=(0.336\pm0.020)\,m_0$ from mid-infrared optical Hall effect measurements. No significant anisotropy of the effective electron mass…

Mid-infrared optical Hall effect measurements are used to determine the free charge carrier parameters of an unintentionally doped wurtzite-structure $c$-plane oriented In$_{0.33}$Ga$_{0.67}$N epitaxial layer. Room temperature electron…

We explore the collective electronic excitations of bilayer molybdenum disulfide (MoS$_2$) using the density functional theory together with the random phase approximation. The many-body dielectric function and electron energy-loss spectra…

Materials Science · Physics 2017-11-15 Zahra Torbatian , Reza Asgari

We report high-resolution inelastic x-ray measurements of the soft phonon mode in the charge-density-wave compound TiSe$_2$. We observe a complete softening of a transverse optic phonon at the L point, i.e. q = (0.5, 0, 0.5), at T ~…

Strongly Correlated Electrons · Physics 2015-05-28 F. Weber , S. Rosenkranz , J. -P. Castellan , R. Osborn , G. Karapetrov , R. Hott , R. Heid , K. -P. Bohnen , A. Alatas

We consider an electron-phonon system in two and three dimensions on square, hexagonal and cubic lattices. The model is a modification of the standard Holstein model where the optical branch is appropriately curved in order to have a…

Statistical Mechanics · Physics 2009-10-31 N. Macris , C. -A. Piguet

This work reports a pulsed laser-assisted synthesis, detailed structural characterization, and study of plasmonic properties of three sets of TiN/TiNO thin films with high electron density. The first two sets of TiN films were grown at 600C…

We measured the Raman and the Infrared phonon spectrum of SmFeAsO polycrystalline samples. We also performed Density Functional Theory calculations within the pseudopotential approximation to obtain the structural and dynamical lattice…

We have systematically investigated the optical properties of the InP1-xBix ternary alloys with 0<x<2.46%, using high resolution polarized Raman scattering measurement. Both InP-like and InBi-like optical vibration modes (LO) were…

Materials Science · Physics 2015-12-16 G. N. Wei , T. Q. Hai , Q. Feng , D. Xing , W. G. Luo , K. Wang , L. Y. Zhang , S. M. Wang , K. Y. Wang

We present absorption coefficient {\alpha}({\omega}), transverse dielectric function {\epsilon}({\omega}), optical conductivity {\sigma}({\omega}), and reflectance R({\omega}) calculated for an emeraldine salt conducting polymer in its…

Materials Science · Physics 2025-08-05 Renato Colle , Pietro Parruccini , Andrea Benassi , Carlo Cavazzoni

We develop a first-principles theory of phonon-assisted optical absorption in semiconductors and insulators which incorporates the temperature dependence of the electronic structure. We show that the Hall-Bardeen-Blatt theory of indirect…

Materials Science · Physics 2015-10-22 Marios Zacharias , Christopher E. Patrick , Feliciano Giustino

We have performed a first principles study of structural, mechanical, electronic, and optical properties of orthorhombic Sb2S3 and Sb2Se3 compounds using the density functional theory within the local density approximation. The lattice…

Materials Science · Physics 2012-05-19 H. Koc , Amirullah M. Mamedov , E. Deligoz , H. Ozisik

We design, test, and analyze fiber-optic voltage sensors based on optical reflection from a piezoelectric transducer. By controlling the physical dimensions of the device, we can tune the frequency of its natural resonance to achieve a…

Systems and Control · Electrical Eng. & Systems 2021-08-02 Joseph M. Lukens , Nicholas Lagakos , Victor Kaybulkin , Christopher J. Vizas , Daniel J. King

We present a density functional theory parametrized hybrid k$\cdot$p tight binding model for electronic properties of atomically thin films of transition-metal dichalcogenides, 2H-$MX_2$ ($M$=Mo, W; $X$=S, Se). We use this model to analyze…

Mesoscale and Nanoscale Physics · Physics 2018-08-07 David A. Ruiz-Tijerina , Mark Danovich , Celal Yelgel , Viktor Zólyomi , Vladimir I. Fal'ko

The phonon density-of-states of transition metal diborides TMB2 with TM = Ti, V, Ta, Nb and Y has been measured using the technique of inelastic neutron scattering. The experimental data are compared with ab initio density functional…

Superconductivity · Physics 2009-11-10 R. Heid , B. Renker , H. Schober , P. Adelmann , D. Ernst , K. -P. Bohnen

We present a tight-binding (TB) model and $\mathbf{k\cdot p}$ theory for electrons in monolayer and few-layer InSe. The model is constructed from a basis of all $s$ and $p$ valence orbitals on both indium and selenium atoms, with…

Mesoscale and Nanoscale Physics · Physics 2017-01-05 S. J. Magorrian , V. Zólyomi , V. I. Fal'ko

The normal state conductivity of a system of interacting large polarons is calculated within the Random Phase approximation and some numerical results are presented. The behaviour of the optical absorption as a function of the charge…

Materials Science · Physics 2007-05-23 V. Cataudella , G. De Filippis , G. Iadonisi

We consider how the infrared intensity of an O-H stretch in a hydrogen bonded complex varies as the strength of the H-bond varies from weak to strong. We obtain trends for the fundamental and overtone transitions as a function of…

Chemical Physics · Physics 2017-03-30 Bijyalaxmi Athokpam , Sai G. Ramesh , Ross H. McKenzie