Acoustic-phonon anomaly in MgB2
نویسندگان
چکیده
منابع مشابه
Phonon modes of MgB2: super-lattice structures and spectral response.
Micrometre-sized MgB2 crystals of varying quality, synthesized at low temperature and autogenous pressure, are compared using a combination of Raman and infra-red (IR) spectroscopy. These data, which include new peak positions in both spectroscopies for high quality MgB2, are interpreted using DFT calculations on phonon behaviour for symmetry-related structures. Raman and IR activity additional...
متن کاملAb initio investigation of collective charge excitations in MgB2.
A sharp collective charge excitation is predicted in MgB2 at approximately 2.5 eV for q perpendicular to the boron layers, based on an all-electron analysis of the dynamical density response within time-dependent density functional theory. This novel excitation, consisting of coherent charge fluctuation between Mg and B sheets, induces an abrupt plasma edge in the experimentally observable refl...
متن کاملThe determination of the electron-phonon interaction from tunneling data in the two-band superconductor MgB2
We calculate the tunneling density of states (DOS) of MgB2 for different tunneling directions, by directly solving the real-axis, two-band Eliashberg equations (EE). Then we show that the numeric inversion of the standard singleband EE, if applied to the DOS of the two-band superconductor MgB2, may lead to wrong estimates of the strength of certain phonon branches (e.g. the E2g) in the extracte...
متن کاملThe reduced total isotope effect and its implications on the nature of superconductivity in MgB2
The recent discovery of superconductivity at ~39 K in MgB2, by Nagamatsu et al.1 establishes this simple binary compound as having the highest bulk superconducting transition temperature, Tc, of any non-copper-oxide material. Much of the initial research has focused on whether MgB2 is a conventional BCS, electron-phonon mediated superconductor, and, if it is, why Tc is so high. Isotope effect m...
متن کاملPhonon dispersion and electron-phonon coupling in MgB2 and AlB2.
We present a first principles investigation of the lattice dynamics and electron-phonon coupling of the superconductor MgB2 and the isostructural AlB2 within the framework of density functional perturbation theory using a mixed-basis pseudopotential method. Complete phonon dispersion curves and Eliashberg functions alpha2F are calculated for both systems. The main differences are related to hig...
متن کامل