title: Dispersion of doppleron-phonon modes in strong coupling regime.
abstract: The dispersion equation for doppleron-phonon modes was constructed and solved analytically in the strong coupling regime. The Fermi surface model proposed previously for calculating the doppleron spectrum in an indium crystal was used. It was shown that in the vicinity of doppleron-phonon resonance, the dispersion curves of coupled modes form a gap qualitatively different from the one observed under helicon-phonon resonance: there is a frequency interval forbidden for existence of waves of definite circular polarization depending upon direction of the external DC magnetic field. The physical reason for it is interaction of the waves which have oppositely directed group velocities.
authors.affiliation: Institute for Metal Physics, Ural Department of the Russian Academy of Sciences, 18, Kovalevskaya St., GSP-170, Yekaterinburg 620219, Russia. gudkov@imp.uran.ru
authors.forename: V V
authors.initials: VV
authors.lastname: Gudkov
authors.forename: I V
authors.initials: IV
authors.lastname: Zhevstovskikh