Quasiparticle properties of small polarons and bipolarons

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

“…Since the Hubbard U is about 1 eV or larger in strongly correlated materials, the electron-phonon coupling must be large to stabilize on-site bipolarons and the Holstein bipolaron mass appears very large, m * * H /m 0 > 1000, for realistic values of phonon frequency. This estimate led some authors to the conclusion that the formation of itinerant small polarons and bipolarons in real materials is unlikely [98], and high-temperature bipolaronic superconductivity is impossible [99]. However, one should note that the Holstein model is an extreme polaron model, and typically yields the highest possible value of the (bi)polaron mass in the strong coupling limit.…”

Polaronic Quasiparticles in a Strongly Correlated Electron Band

“…Nearly all these studies have been confined to models with only one or two electrons, and do not include the electron spin. Such models have limited applicability and there is a need for studies of more realistic many-electron situations 1 . There are technical problems, however, in handling such models as non-perturbative methods are required to describe the effects of strong electron-lattice interactions and few such methods are applicable to the manyelectron case.…”

Dimensionality effects on the Su–Schrieffer–Heeger model

“…Note that the absorption spectra broaden (both in 1D and 2D) by enhancing the strength of the e-ph coupling as a consequence of the mixing of electronic states and lattice vibrational excitations. Although comparisons with specific data are not possible at this stage, broad photoemission spectra are known [7,19,44] to be a feature of systems with polaronic charge carriers.…”

“…A wide literature has been produced on the subject during the last decades [2][3][4][5][6][7][8] and particular emphasis has been recently laid on the polaronic properties of high T c superconductors [9]. As the spatial extension of the lattice deformation can vary, the concepts of large and small polaron have been introduced: the transition between a large and a small polaron state is driven by the strength of the electron-phonon coupling [10][11][12][13] and monitored through the behavior of ground state properties such as the polaron energy band and the effective mass [14][15][16].…”