3 research outputs found
Green's and spectral functions of the small Frolich polaron
According to recent Quantum Monte Carlo simulations the small polaron theory
is practically exact in a wide range of the long-range (Frohlich)
electron-phonon coupling and adiabatic ratio. We apply the Lang-Firsov
transformation to convert the strong-coupling term in the Hamiltonian into the
form of an effective hopping integral and derive the single-particle Green's
function describing propagation of the small Frohlich polaron. One and two
dimensional spectral functions are studied by expanding the Green's function
perturbatively. Numerical calculations of the spectral functions are produced.
Remarkably, the coherent spectral weight (Z) and effective mass (Z')
renormalisation exponents are found to be different with Z'>>Z, which can
explain a small coherent spectral weight and a relatively moderate mass
enhancement in oxides.Comment: RevTeX, 5 pages, 2 postscript figures, LaTeX processing problems
correcte
Theory of SIS tunnelling in cuprates
We show that the single-particle polaron Green's function describes SIS
tunnelling in cuprates, including the absence of Ohm's law at high voltages,
the dip/hump features in the first derivative of the current, a substantial
incoherent spectral weight beyond quasiparticle peaks and unusual shape of the
peaks.
The theory allows us to determine the characteristic phonon frequencies,
normal and superconducting gaps, impurity scattering rate, and the
electron-phonon coupling from the tunnelling data.Comment: 10 pages, 2 figure
Small Froehlich polaron Green's function and tunnelling in cuprates
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