Theory of Superconducting $T_{c}$ of doped fullerenes

Details Theory of Superconducting $T_{c}$ of doped fullerenes Theory of Superconducting $T_{c}$ of doped fullerenes

1996-02-27

arxiv.org/abs/cond-mat/9602139v1

Physics

Condensed Matter

20 pages, Latex, 4 figures available upon request

Scientific paper

10.1103/PhysRevB.54.3655

We develop the nonadiabatic polaron theory of superconductivity of $M_{x}C_{60}$ taking into account the polaron band narrowing and realistic electron-phonon and Coulomb interactions. We argue that the crossover from the BCS weak-coupling superconductivity to the strong-coupling polaronic and bipolaronic superconductivity occurs at the BCS coupling constant $\lambda\sim 1$ independent of the adiabatic ratio, and there is nothing ``beyond'' Migdal's theorem except small polarons for any realistic electron-phonon interaction. By the use of the polaronic-type function and the ``exact'' diagonalization in the truncated Hilbert space of vibrons (``phonons'') we calculate the ground state energy and the electron spectral density of the $C_{60}^{-}$ molecule. This allows us to describe the photoemission spectrum of $C_{60}^{-}$ in a wide energy region and determine the electron-phonon interaction. The strongest coupling is found with the high-frequency pinch $A_{g2}$ mode and with the Frenkel exciton. We clarify the crucial role of high-frequency bosonic excitations in doped fullerenes which reduce the bare bandwidth and the Coulomb repulsion allowing the intermediate and low-frequency phonons to couple two small polarons in a Cooper pair. The Eliashberg-type equations are solved for low-frequency phonons. The value of the superconducting $T_{c}$, its pressure dependence and the isotope effect are found to be in a remarkable agreement with the available experimental data.

Affiliated with

Also associated with

No associations

Rating

Theory of Superconducting $T_{c}$ of doped fullerenes does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Theory of Superconducting $T_{c}$ of doped fullerenes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Theory of Superconducting $T_{c}$ of doped fullerenes will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-3762