Response functions of two-coupled chains of Tomonaga–Luttinger liquids

Abstract

Properties of fluctuations in two chains of Tomonaga–Luttinger liquids coupled by the interchain hopping have been studied by calculating retarded response functions χ ρ R( q x , q y ; ω) for charge and χ σ R( q x , q y ; ω) for spin where q x and q y (=0 or π) denote the longitudinal and transverse wave vector, respectively, and ω is the frequency. We have found the notable fact that the repulsive intrachain interaction results in the clear enhancement of Im χ σ R( q x , π; ω) and the suppression of Im χ ρ R( q x , π; ω) at low energies. This result indicates the importance of the dynamical effect by the spin fluctuation with q y = π and small ω, which has a possibility to give rise to the attractive interaction for the electron pairing.