2010/10/31 by D. J. J. Marchand, G. De Filippis, V. Cataudella +5 · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.105.266605
published as D.J.J. Marchand, G. De Filippis, V. Cataudella, M. Berciu, N. Nagaosa, N.V. Prokof'ev, A.S. Mishchenko, and P.C.E. Stamp, Physical Review Letters 105, 266605 (2010)
arxiv created 2011/02/01 · arxiv updated 2015/03/17
We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show a smooth crossover from weak to strong coupling, as a function of the electron-phonon coupling strength λ, in all models where this coupling depends only on phonon momentum q. In the SSH model the coupling also depends on the electron momentum k; we find it has a sharp transition, at a critical coupling strength λc, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at λ= λc, except the average number of phonons in the polaronic cloud. This result is representative of all polarons with coupling depending on k and q, and will have important experimental consequences (eg., in ARPES and conductivity experiments).