Critical Ising modes in low-dimensional Kondo insulators

TL;DR

This paper explores a novel intermediate phase in one-dimensional Kondo insulators characterized by critical Ising modes resulting from spinon splitting, with implications for understanding magnetic excitations and phase stability.

Contribution

It introduces an Ising-like intermediate phase with critical excitations in 1D Kondo insulators, highlighting the role of RKKY interactions and instability of the chiral fixed point.

Findings

Existence of an Ising-like intermediate phase with critical modes.

Spectral gap in the triplet sector under certain conditions.

Paramagnetic disordered state influenced by Kondo model correlation length.

Abstract

We present an Ising-like intermediate phase for one-dimensional Kondo insulator systems. Resulting from a spinon splitting, its low-energy excitations are critical Ising modes, whereas the triplet sector has a spectral gap. It should occur as long as the RKKY oscillation amplitude dominates over any direct exchange between localized spins. The chiral fixed point, however, becomes unstable in the far Infra-Red limit due to prevalent fluctuations among localized spins which induce gapless triplet excitations in the spectrum. Based on previous numerical results, we obtain a paramagnetic disordered state ruled by the correlation length of the single impurity Kondo model.