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Raman Scattering in Os: Nonadiabatic Renormalization of the Optical Phonon Self‐Energies
Author(s) -
Ponosov Yu. S.,
Bolotin G. A.,
Thomsen C.,
Cardona M.
Publication year - 1998
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199807)208:1<257::aid-pssb257>3.0.co;2-f
Subject(s) - phonon , anisotropy , brillouin zone , condensed matter physics , raman spectroscopy , physics , raman scattering , x ray raman scattering , polarization (electrochemistry) , isotropy , scattering , wave vector , atomic physics , chemistry , optics
The wave vector dependence of the E 2g optical phonon frequencies and linewidths in the hexagonal close‐packed metal, osmium, was studied at 10 K. A strong anisotropic dispersion, as well as damping thresholds, were observed for two transverse branches in the high‐symmetry directions of the Brillouin zone around a phonon wave vector magnitude of 10 6 cm −;1 . Simultaneously, a continuum was found in the Raman spectra, presumably of electronic nature, whose q ‐dependence correlates with that the phonon self‐energies. Numerical simulations of the electronic Raman response in terms of an intraband mechanism were performed with a model energy‐band spectrum reproducing the main features of the Fermi surface anisotropy of Os. A large discrepancy was found between the calculated and the measured anisotropy of the electronic scattering with respect to momentum direction and polarization configuration. The possible assignment to a contribution of resonant terms to the Raman vertex is discussed.