Spin Gap in a Doped Kondo Chain

TL;DR

This paper demonstrates that doping a Kondo chain induces a spin gap when a direct Heisenberg interaction is added, with analysis spanning weak to strong coupling regimes using bosonization and t-J model mappings.

Contribution

It reveals the conditions under which a spin gap appears in a doped Kondo chain with additional Heisenberg coupling, bridging weak and strong coupling analyses.

Findings

Spin gap appears upon doping with added Heisenberg coupling.

The spin gap phase exists for specific fillings and coupling ranges.

Analysis covers both weak and strong coupling regimes.

Abstract

We show that the Kondo chain away from half-filling has a spin gap upon the introduction of an additional direct Heisenberg coupling between localized spins. This is understood in the weak-Kondo-coupling limit of the Heisenberg-Kondo lattice model by bosonization and in the strong-coupling limit by a mapping to a modified t-J model. Only for certain ranges of filling and Heisenberg coupling does the spin gap phase extend from weak to strong coupling.