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Theory of Cyclotron Resonance of Fröhlich Polarons in High Magnetic Fields
Author(s) -
Evrard R.,
Kartheuser E.,
Devreese J.
Publication year - 1970
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.19700410148
Subject(s) - polaron , excited state , cyclotron resonance , condensed matter physics , electron cyclotron resonance , physics , magnetic field , phonon , cyclotron , atomic physics , fourier transform ion cyclotron resonance , ion cyclotron resonance , electron , ionic bonding , resonance (particle physics) , coupling (piping) , ion , materials science , quantum mechanics , metallurgy
Cyclotron resonance of polarons in ionic crystals is studied by means of a Born‐Oppenheimer type method. The Lee, Low, Pines approximation is made for the electron—phonon interaction and so the translational invariance along the magnetic field direction is exploited. Our approach is therefore valid at weak and intermediate couplings and cyclotron frequencies ω c larger than the L.O. phonon frequency ω, which requires rather intense magnetic fields. For relatively large electron—phonon coupling (α ≧ 4) the results also apply qualitatively for weak magnetic fields. The ground state energy and the energy of two excited levels are obtained. The excited states which are treated here are internal excited states of the polaron system and they are different from the normal Landau levels. The stability of some of these states is enhanced under the action of the magnetic field. This leads us to predict absorption at new cyclotron frequencies in ionic crystals especially relevant for intermediate coupling strengths α ≈ 4.