Spectroscopic indications of polaronic carriers in the quasi-one-dimensional conductor (TaSe₄)₂I

A Fermi surface crossing in the metallic phase based on the identification of the polaronic quasiparticle (QP) dispersion with the leading edge of the spectrum was observed. The underlying quasiparticles consist of vanishing spectral weight and short coherence lengths. The numerical simulations of the polaron models produced complex spectral functions. The results indicated that polarons were simple excitations which might be described in terms of the lowest nonvanishing moments of the weighted eigenstates and their dependence on wave numbers.