Open AccessPuzzling phonon dispersion curves and vibrational mode instability in superconducting MgCNi3
Author(s) -
Prafulla K. Jha,
Sheifali Gupta,
Sanjeev K. Gupta
Publication year - 2012
Publication title -
aip advances
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 58
ISSN - 2158-3226
DOI - 10.1063/1.4714366
Subject(s) - phonon , condensed matter physics , superconductivity , inelastic neutron scattering , brillouin zone , inelastic scattering , debye model , physics , instability , scattering , dispersion (optics) , phonon scattering , density of states , quantum mechanics
A first principles calculation of the lattice dynamical properties of superconducting MgCNi3 has been performed using density functional perturbation theory (DFPT). The calculated phonon dispersion curves and phonon density of states have been compared with inelastic x-ray scattering (IXS) and inelastic neutron scattering (INS) measurements. We show for the first time that phonon dispersion curves for MgCNi3 in whole Brillouin zone are positive (stable phonon modes) and in good agreement with the experimental data. The phonon DOS shows absence of phonon density of states at zero energy unlike earlier calculations. There is a good agreement between calculated and experimental electron-phonon parameter and superconducting transition temperature. The Eliasberg function is quantitatively as well as qualitatively different from the phonon density of states. The lattice specific heat and Debye temperature do not show any anomalous behaviour