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We show that the usual expression for evaluating electron-phonon coupling and the phonon linewidth in 2D metals with a cylindrical Fermi surface cannot be applied near the wave vector corresponding to the Kohn singularity. Instead, the…

Superconductivity · Physics 2009-11-13 O. V. Dolgov , O. K. Andersen , I. I. Mazin

Kohn anomalies in three-dimensional metallic crystals are dips in the phonon dispersion that are caused by abrupt changes in the screening of the ion-cores by the surrounding electron-gas. These anomalies are also present at the…

Mesoscale and Nanoscale Physics · Physics 2013-11-19 F. Forster , A. Molina-Sanchez , S. Engels , A. Epping , K. Watanabe , T. Taniguchi , L. Wirtz , C. Stampfer

Twisted bilayer graphene (TBG) has attracted great interest in the last decade due to the novel properties it exhibited. It was revealed that e-phonon interaction plays an important role in a variety of phenomena in this system, such as…

Mesoscale and Nanoscale Physics · Physics 2024-10-29 Jun-Wei Li , Jia-Xing Zhang , Wei Chen

Inelastic light scattering studies on single crystal of electron-doped Ca(Fe0.95Co0.05)2As2 superconductor, covering the tetragonal to orthorhombic structural transition as well as magnetic transition at TSM ~ 140 K and superconducting…

We have performed ellipsometric measurements of the far-infrared c-axis dielectric response of underdoped YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ single crystals. Here we report a detailed analysis of the temperature-dependent renormalization of…

Superconductivity · Physics 2016-08-15 C. Bernhard , D. Munzar , A. Golnik , C. T. Lin , A. Wittlin , J. Humlíček , M. Cardona

We compute, from first-principles, the frequency of the E2g, Gamma phonon (Raman G-band) of graphene, as a function of the charge doping. Calculations are done using i) the adiabatic Born-Oppenheimer approximation and ii) time-dependent…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Michele Lazzeri , Francesco Mauri

Cuprate superconductors host a multitude of low-energy optical phonons. Using time- and angle-resolved photoemission spectroscopy, we study coherent phonons in Bi$_{2}$Sr$_{2}$Ca$_{0.92}$Y$_{0.08}$Cu$_{2}$O$_{8+\delta}$. Sub-meV modulations…

Strongly Correlated Electrons · Physics 2019-05-07 S. -L. Yang , J. A. Sobota , Y. He , D. Leuenberger , H. Soifer , H. Eisaki , P. S. Kirchmann , Z. -X. Shen

Super-high resolution laser-based angle-resolved photoemission spectroscopy measurements have been carried out on a heavily overdoped (Bi,Pb)2Sr2CuO6 (Tc> 5 K) superconductor. Taking advantage of the high-precision data on the subtle change…

We report measurements of the phonon density of states as measured with inelastic x-ray scattering in SmFeAsO$_{1-x}$F$_y$ powders. An unexpected strong renormalization of phonon branches around 23 meV is observed as fluorine is substituted…

We report a study of the lattice dynamics in superconducting NaFeAs (Tc = 8 K) and doped NaFe0.97Co0.03As (Tc = 20 K) using Raman light scattering. Five of the six phonon modes expected from group theory are observed. In contrast with…

Superconductivity · Physics 2016-11-25 Y. J. Um , Yunkyu Bang , B. H. Min , Y. S. Kwon , M. Le Tacon

Typical density-functional theory calculations that wrongly predict undoped cuprates to be metallic also predict Cu-O half- and full-breathing phonon energies that are significantly softer than observed, presumably because of weak on-site…

Strongly Correlated Electrons · Physics 2021-11-03 Tyler C. Sterling , Dmitry Reznik

Electron-phonon coupling (EPC) in bilayer graphene (BLG) at different doping levels is studied by first-principles calculations. The phonons considered are long-wavelength high-energy symmetric (S) and antisymmetric (AS) optical modes. Both…

Materials Science · Physics 2013-03-26 Jia-An Yan , K. Varga , M. Y. Chou

We estimate the effect of the superconducting gap anisotropy in the dispersive gap mode of phonons, which is observed by the neutron scattering on borocarbide superconductors. We numerically analyze the phonon spectrum considering the…

Superconductivity · Physics 2007-08-01 Masanori Ichioka , Kazushige Machida

We report a combined study of the spin resonances and superconducting gaps for underdoped ($T_c=19$ K), optimally doped ($T_c=25$ K), and overdoped ($T_c=19$ K) Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals with inelastic neutron…

Effect of doping on the carrier-phonon interaction in wurtzite GaN is investigated by pump-probe reflectivity measurements using 3.1 eV light in near resonance with the fundamental band gap of 3.39 eV. Coherent modulations of the…

Materials Science · Physics 2013-05-09 Kunie Ishioka , Keiko Kato , Naoki Ohashi , Hajime Haneda , Masahiro Kitajima , Hrvoje Petek

A remarkable hardening (~ 30 cm-1) of the normal mode of vibration associated with the symmetric stretching of the oxygen octahedra for the Ba2FeReO6 and Sr2CrReO6 double perovskites is observed below the corresponding magnetic ordering…

The transport and magnetic properties of correlated La{0.53}Sr{0.47}MnO{3} ultrathin films, grown epitaxially on SrTiO{3}, show a sharp cusp at the structural transition temperature of the substrate. Using a combination of experiment and…

Materials Science · Physics 2011-09-09 Y. Segal , K. F. Garrity , C. A. F. Vaz , J. D. Hoffman , F. J. Walker , S. Ismail-Beigi , C. H. Ahn

We present a study of the soft transverse optic phonon mode in SnTe in comparison to the corresponding mode in PbTe using inelastic neutron scattering and ab-initio lattice dynamical calculations. In contrast to previous reports our…

Materials Science · Physics 2022-01-21 Zehua Li , Shasha Li , John-Paul Castellan , Rolf Heid , Yu Xiao , Li-Dong Zhao , Yue Chen , Frank Weber

In cavity optomechanics, nanomechanical motion couples to a localized optical mode. The regime of single-photon strong coupling is reached when the optical shift induced by a single phonon becomes comparable to the cavity linewidth. We…

Mesoscale and Nanoscale Physics · Physics 2013-04-22 Max Ludwig , Amir H. Safavi-Naeini , Oskar Painter , Florian Marquardt

Realising scalable quantum networks requires a meticulous level of understanding and mitigating the deleterious effects of decoherence. Many quantum device platforms feature multiple decoherence mechanisms, often with a dominant mechanism…

Quantum Physics · Physics 2023-08-17 Julian Wiercinski , Erik M. Gauger , Moritz Cygorek
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