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Plasmapolaron selfenergy and effective mass in uniaxial polar crystals
Author(s) -
Capone G.,
Cataudella V.,
Ninno D.,
Iadonisi G.
Publication year - 1996
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/pssb.2221970213
Subject(s) - condensed matter physics , polaron , electron , plasmon , physics , quasiparticle , effective mass (spring–mass system) , phonon , anisotropy , superconductivity , optics , quantum mechanics
We study the polaron effects in a uniaxial polar semiconductor with electrons in the conduction band. We describe the system as an external charge interacting with three boson fields: two optical longitudinal phonons and a plasmon. The combined effects of these three fields lead to a quasiparticle which we call plasmapolaron. The selfenergy and the anisotropic effective mass of the plasmapolaron as a function of the anisotropy parameters and the electron density are calculated in the intermediate regime for the electron‐phonon and electron‐plasmon coupling. We find that, when the crystal has high polarizability along the c ‐axis and a large polaron radius in the a‐b plane, the screening effects due to the plasmons on the electron‐phonon interaction are small, so that the latter is present even at relatively high electron density. In these conditions the induced charges are localized mainly on the a ‐ b plane. We also calculate the selfenergy of the plasmapolaron in the strong coupling limit and compare it with that calculated in the intermediate regime. We find that, increasing the electron density, the selfenergy in the intermediate regime becomes always lower than that in the strong limit. A possible connection of our results with the high‐T c superconductors is discussed.