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Synchrotron infrared measurements were conducted over the range 100 to 8000 cm-1 on a self-doped LaxMnO3-d (x~~0.8) film. From these measurements we determined the conductivity, the effective number of free carriers, and the specific phonon…

Materials Science · Physics 2009-11-13 P. Gao , T. A. Tyson , Z. Liu , M. A. DeLeon , C. Dubourdieu

Using the Eliashberg theory of superconductivity we have examined several properties of a model in which electrons are coupled only to rattling phonon modes represented by a sharp peak in the electron-phonon coupling function. Our choice of…

Superconductivity · Physics 2018-07-13 Samin Tajik , Božidar Mitrović , Frank Marsiglio

We investigate the physical properties of the Ba$_{1-x}$K$_x$BiO$_3$ compounds with a focus on the optical properties. Results from the simple Holstein model, describing a single band coupled to an oxygen breathing mode with parameters…

Strongly Correlated Electrons · Physics 2012-07-13 R. Nourafkan , F. Marsiglio , G. Kotliar

We present the optical reflectance and conductivity spectra for non-oxide antiperovskite superconductor $MgCNi_{3}$ at different temperatures. The reflectance drops gradually over a large energy scale up to 33,000 cm$^{-1}$, with the…

Superconductivity · Physics 2009-11-11 P. Zheng , J. L. Luo , G. T. Liu , Y. L. Zhang , R. C. Yu , C. Q. Jin , N. L. Wang , M. Q. Tan

The magnetic susceptibility between 1.5 and 800 K, the infrared reflectivity at room temperature and the temperature dependence of the dielectric constant at mm-wavelengths are reported for single crystalline BiFeO3. A well developed…

Strongly Correlated Electrons · Physics 2010-07-22 Jun Lu , M Schmidt , P Lunkenheimer , A Pimenov , A A Mukhin , V D Travkin , A Loidl

We present an exploration of the effect of electron-phonon coupling and broken inversion symmetry on the electronic and thermal properties of the semimetal LaRhGe$_3$. Our transport measurements reveal evidence for electron-hole…

Using a combination of infrared ellipsometry, time-domain terahertz spectroscopy, and far-infrared reflectometry we have obtained the $ac$-plane complex dielectric function of monoclinic ($C2/c$) Ta$_2$NiSe$_5$ and orthorhombic ($Cmcm$)…

Strongly Correlated Electrons · Physics 2018-09-12 T. I. Larkin , R. D. Dawson , M. Höppner , T. Takayama , M. Isobe , Y. -L. Mathis , H. Takagi , B. Keimer , A. V. Boris

We investigated a high-quality MgB$_{2}$ thin film with a thickness of $\sim$1000 nm on an Al$_{2}$O$_{3}$ substrate using optical spectroscopy. We measured the reflectance spectra of the film at various temperatures both below, and above,…

Superconductivity · Physics 2018-08-21 Yu-Seong Seo , Jae Hak Lee , Won Nam Kang , Jungseek Hwang

We performed a polarized Raman scattering study of quasi-one-dimensional superconductor K$_2$Cr$_3$As$_3$. We detect two A$_1^\prime$ phonons and three E$^\prime$ phonons. One of the A$_1^\prime$ modes exhibits a nearly…

Superconductivity · Physics 2015-08-19 W. -L. Zhang , H. Li , Dai Xia , H. W. Liu , Y. -G. Shi , J. L. Luo , Jiangping Hu , P. Richard , H. Ding

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

Polar phonons of HgCr2S4 and CdCr2S4 are studied by far-infrared spectroscopy as a function of temperature and external magnetic field. Eigenfrequencies, damping constants, effective plasma frequencies and Lyddane-Sachs-Teller relations,…

Strongly Correlated Electrons · Physics 2008-06-26 T. Rudolf , Ch. Kant , F. Mayr , J. Hemberger , V. Tsurkan , A. Loidl

We have investigated the charge dynamics of VO2 by optical reflectivity measurements. Optical conductivity clearly shows a metal-insulator transition. In the metallic phase, a broad Drude-like structure is observed. On the other hand, in…

Strongly Correlated Electrons · Physics 2009-11-11 K. Okazaki , S. Sugai , Y. Muraoka , Z. Hiroi

Exciton dynamics can be strongly affected by lattice vibrations through electron-phonon coupling. This is rarely explored in two-dimensional magnetic semiconductors. Focusing on bilayer CrI3, we first show the presence of strong…

We have measured the near-normal reflectance of Tl2Ba2CaCu2O8 (Tl2212) for energies from 0.1 to 4.0 eV at room temperature and used a Kramers-Kronig analysis to find the complex, frequency dependent dielectric function, from which the…

We report temperature-dependent Raman scattering and X-ray diffraction studies of pyrochlore iridates, (Eu$_{1-x}$Bi$_x$)$_2$Ir$_2$O$_7$, for x=0, 0.02, 0.035, 0.05 and 0.1. The temperature variation in Raman experiments spans from 4 K to…

Strongly Correlated Electrons · Physics 2022-03-14 Anoop Thomas , Prachi Telang , Kshiti Mishra , Martin Cesnek , Jozef Bednarcik , D V S Muthu , Surjeet Singh , A K Sood

We present the results of pressure-dependent far-infrared reflectivity measurements on the multiferroic perovskite BiFeO3 at room temperature. The observed behavior of the infrared-active phonon modes as a funtion of pressure clearly…

Other Condensed Matter · Physics 2007-12-06 A. Pashkin , K. Rabia , S. Frank , C. A. Kuntscher , R. Haumont , R. Saint-Martin , J. Kreisel

We report a comprehensive investigation of the lattice dynamics of URu$_2$Si$_2$ as a function of temperature using Raman scattering, optical conductivity and inelastic neutron scattering measurements as well as theoretical {\it ab initio}…

We have investigated the infrared and Raman optical properties of BaMn2As2 in the ab-plane and along the c-axis. The most prominent features in the infrared spectra are the Eu and A2u phonon modes which show clear TO-LO splitting from the…

Superconductivity · Physics 2012-07-11 A. Antal , T. Knoblauch , Y. Singh , P. Gegenwart , D. Wu , M. Dressel

We examined the temperature (T) evolution of the optical conductivity spectra of Sr$_3$Ir$_2$O$_7$ over a wide range of 10-400 K. The system was barely insulating, exhibiting a small indirect bandgap of $\sim$0.1 eV. The low-energy features…

Strongly Correlated Electrons · Physics 2015-06-18 H. J. Park , C. H. Sohn , D. W. Jeong , G. Cao , K. W. Kim , S. J. Moon , Hosub Jin , Deok-Yong Cho , T. W. Noh

How electron-phonon interactions influence high-temperature superconductivity in cuprates remains contested, and their role outside the CuO$_2$ planes has been largely overlooked. The most conspicuous evidence for such coupling is the…