Physical review. B, Solid state
Single-particle states in weakly coupled linear chains
H. G. Schuster
Abstract
The validity of the quasiparticle picture for electrons in weakly coupled linear chains is investigated using for a single chain the Tomonaga-Luttinger model of interacting one-dimensional electrons. For interchain coupling without jumps between the chains it is proved exactly that no stable quasiparticles exist. The excitation spectrum is exhausted by density oscillations and the single-particle occupation number shows a power-law behavior. For finite-interchain hopping, lowest-order-perturbation theory yields a quasiparticle peak in the spectral density. Its weight is $z={[1\ensuremath{-}2\ensuremath{\alpha}\mathrm{ln}(\frac{{W}_{\ensuremath{\perp}}}{{W}_{\ensuremath{\parallel}}})]}^{\ensuremath{-}1}$, where $\ensuremath{\alpha}$ is the interaction parameter and ${W}_{\ensuremath{\parallel}}$ and ${W}_{\ensuremath{\perp}}$ are the widths of the conduction band in momentum direction parallel and perpendicular to the chains. The relevance of our results for real quasi-one-dimensional conductors will be discussed.