2005/04/30 by K. Ziegler, D. Schneider · 1 citation
Physics and Astronomy · #cond-mat.str-el
paper · pdf · doi:10.1088/0953-8984/17/36/005
published as J. Phys.: Condens. Matter 17, 5489-5497 (2005) · 11 pages, 3 figures, revised and published version
arxiv created 2005/09/20 · arxiv updated 2009/12/01
A model with Holstein-like electron-phonon coupling is studied in the limit of adiabatic phonons. The phonon distribution is anharmonic with two degenerate maxima. This model can be related to fermions in a correlated binary alloy and describes microscopic phase separation. We discuss the weak and strong electron-phonon coupling limit and present a qualitative phase diagram. In terms of the phononic displacements it consists of a homogeneous, an alternating, and a disordered phase. There is a first order phase transition between the homogeneous and the alternating phase, and second order phase transition between the alternating and the disordered phase. The opening of a gap inside the disordered phase is treated by a dynamical mean-field theory.