“School of Physics”
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| Paper IPM / P / 7231 |
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| Abstract: | |||||||||
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We evaluate the elementary excitations of both spin-singlet and
spin-triplet paired crystalline phases of a two-dimensional system
of electrons in a perpendicular magnetic field. We use the
harmonic Hamiltonian derived from a truncation of the intercell
interactions at dipolar terms and treat it within a circular-cell
approximation. At this level the excitations are of two types,
i.e. a discrete spectrum of localized vibrorotational modes and a
continuum of dispersive magneto-oscillations. The eigenfunctions
and eigenfrequencies of the intracell dynamics depend on a single
parameter, which contains the electron density and the magnetic
length, and are exhibited as functions of this parameter for
various sets of values of the radial and angular-momentum quantum
numbers. The propagating excitations describe collective
oscillations of the centre of mass of the electron pairs and
derive, as in the usual unpaired crystal phase, from the
magnetic-field-induced shifts of plasmons and transverse phonons
of the crystal in zero field. Several illustrations of their
dispersion curves are given. Possible extensions of the theory to
include anharmonicity and higher intercell couplings are briefly
discussed.
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