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 , 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 c, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at ¼ c. This result is representative of all polarons with coupling depending on k and q, and will have important experimental consequences (e.g., in angle-resolved photoemission spectroscopy and conductivity experiments).
Sharp Transition for Single Polarons in the One-Dimensional Su-Schrieffer-Heeger Model / D. J. J., Marchand; DE FILIPPIS, Giulio; Cataudella, Vittorio; M., Berciu; N., Nagaosa; N. V., Prokof'Ev; A. S., Mishchenko; P. C. E., Stamp. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - STAMPA. - 105:(2010), pp. 266605-1-266605-4. [10.1103/PhysRevLett.105.266605]
Sharp Transition for Single Polarons in the One-Dimensional Su-Schrieffer-Heeger Model
DE FILIPPIS, GIULIO;CATAUDELLA, VITTORIO;
2010
Abstract
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 , 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 c, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at ¼ c. This result is representative of all polarons with coupling depending on k and q, and will have important experimental consequences (e.g., in angle-resolved photoemission spectroscopy and conductivity experiments).File | Dimensione | Formato | |
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