Open AccessElectron‐phonon interaction in correlated electronic systems: polarons and the formation of orbital ordering
Author(s) -
Schneider D.,
Höck K.H.,
Ziegler K.
Publication year - 2004
Publication title -
physica status solidi (c)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 46
eISSN - 1610-1642
pISSN - 1610-1634
DOI - 10.1002/pssc.200405359
Subject(s) - polaron , hubbard model , condensed matter physics , physics , jahn–teller effect , atomic orbital , lattice (music) , fermion , electron , quantum mechanics , coupling constant , superconductivity , ion , acoustics
The properties of a dilute electron gas, coupled to the lattice degrees of freedom, are studied and compared with the properties of an electron gas at half‐filling, where spinless fermions with two orbitals per lattice site are considered. The simplest model which includes both the local electron‐lattice interaction of the Jahn‐Teller type and the electronic correlations is the E ⊗ β ‐Jahn‐Teller‐Hubbard model. We analyze the formation and stability of Jahn‐Teller polarons and bipolarons, respectively. Our approach is based on a hopping expansion in the strong‐coupling regime. The results are compared with recently published findings for the Hubbard‐Holstein model [1, 2]. The special case of the Jahn‐Teller‐Hubbard model at half‐filling is mapped on a spin‐1/2 Heisenberg model with phonon‐dependent coupling constants. This has been derived within a projection formalism that provides a continued‐fraction representation of the Green's function. We study the exact solution for two and three particles and compare it with the effective theory on the infinite lattice with one particle per site. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)