One-Dimensional Kondo Lattice at Half Filling: Charge Properties

Abstract

The model of Kondo chain with $M$-fold degenerate band of conduction electrons of spin 1/2 at half filling interacting with localized spins $S$ is studied. It is shown that due to the instanton effects the spin sector reveals itself in optical conductivity. Namely, the density of the charge current at large wave vector $k \approx π$ is proportional to the density of topological charge of the staggered magnetization. As a consequence, the optical conductivity at $k = π$ would either have a gap equal to three spin gaps (for $|M - 2S| = $(even) when the spin spectrum is gapful), or show a psedogap $σ(ω, k = π) \sim ω^2$ for $|M - 2S|$ = (odd).