Effect of internal excitations of polarons on magneto‐optical absorption and cyclotron resonance in polar crystals

Devreese, Jozef T.; Kartheuser, E.; Ward, Robert W.; Baldereschi, A.

doi:10.1002/pssb.2220590231

Cited by 13 publications

References 23 publications

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Mean field theory of a single fröhlich polaron possible existence of phase transitions

Lépine

Matz

1979

Physica Status Solidi (b)

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New results for the free polaron ground state energy are presented, based on a non-perturbative Fock approximation mean field theory. From variational calculations a new energy upper bound for all couplings is obtained, whose newness lies in its cylindrical symmetry, thu sbreaking the spherical symmetry of the Frohlich Hamiltonian. For a (the electron-phonon coupling constant)s3 a translational invariant state is found, for 3 5 a 3.8 a two-dimensional localized state while for a 2 3.8, a three-dimensional, cylindrical localized state is obtained. By $inking the variational approach to a dynamical approximation of the Frohlich Hamiltonian, the possibility is suggested of second-order phase transitions for the structure of the polaron, in the framework of the Bock approximation.Nous prBsentons de nouveaux rbsultats, pour l'bnergie de I'btat fondamental du polaron libre. 11s sont bases sur l'approximation de Fock, une theorie de champ moyen non-perturbative. A partir de calculs variationels, nous obtenons une nouvelle borne supbrieure B 1'8nergie pour tous couplages, dont la nouveautB rbside dans sa symetrie cylindrique, brisant la symetrie sphBrique du hamiltonien de Frohlich. Pour la couplage Blectron-phonon a 5 3, nous trouvons un btat translationnellemeiit invariant, pour 3 a 5 3,8 nous trouvons une localisation b-idimensionnelle et pour a 2 3,8, nous obtenons un &tat de localisation tri-dimensionnelle cylindrique. En reliant l'approche variationnelle A une approximation dynamique du hamiltonien de Frohlich, nous suggdrons la possibilitb de transition de phase de 2e espbce pour la structure du polaron, dam le cadre de l'approximation de Fock. IntroductionThe ground state energy of the large dielectric polaron, as introduced by Frohlich [l], has been studied for many years by a great variety of techniques. Of these, mean field theories have turned out to be useful for investigation of the ground state energy for the whole interaction range. An important feature of these mean field theories is their variational character, which is their strongest feature, one that also permitted actual computation. The theories in question are those of Feynman Here, it is our purpose to present some new qualitative and quantitative results, based on the mean field approximation of Matz and Burkey [5]. The latter theory lends itself, for reasons t o be elaborated later, t o explore the possibility of estimating the ground state energy within symmetry subgroups of the whole Hamiltonian. Furthermore, this mean field theory also suggests the possibility that the Frohlich Hamiltonian exhibits phase transitions (for one electron interacting with an infinite number of virtual phonons and a t zero temperature) as a function of the coupling constant (the ordered state being the cooperative, correlated strong coupling regime

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Mean field theory of a single fröhlich polaron possible existence of phase transitions

Lépine

Matz

1979

Physica Status Solidi (b)

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Rigorous Ground State Energy of a Linearized Model of a Polaron in a Magnetic Field

Brosens

Devreese

1988

Physica Status Solidi (b)

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An explicit analytical expression is derived for the ground state energy of a linearized polaron model in a constant and uniform magnetic field. I n this model, the validity of the Feynman inequality in a magnetic field is investigated. In a fixed magnetic field, it is shown that even for arbitrarily small electron-phonon coupling, the presence of a magnetic field is prohibitive for the application of the Feynman inequality.Es wird ein expliziter analytischer Ausdruck fur die Grundzustandsenergie eines linearisierten Polaronenmodells in einem konstanten und gleichformigen Magnetfeld abgeleitet. I n diesem Modell wird die Gultigkeit der Feynmanungleichheit in einem Magnetfeld untersucht. Es wird gezeigt, daB insbesonders fur beliebig kleine Elektron-Phonon-Kopplung die Anwesenheit eines Magnetfeldes die Anwendung der Feynman-Ungleichung verbietet.

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A magnetic field induced two-dimensional stripping of the polaron

Peeters¹,

Devreese²

Application of High Magnetic Fields in Semiconductor Physics

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Effect of internal excitations of polarons on magneto‐optical absorption and cyclotron resonance in polar crystals

Cited by 13 publications

References 23 publications

Mean field theory of a single fröhlich polaron possible existence of phase transitions

Mean field theory of a single fröhlich polaron possible existence of phase transitions

Rigorous Ground State Energy of a Linearized Model of a Polaron in a Magnetic Field

A magnetic field induced two-dimensional stripping of the polaron

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