Hidden Multiple-spin Interactions as an Origin of Spin Scalar Chiral Order in Frustrated Kondo Lattice Models

TL;DR

This paper uncovers how hidden kinetic-driven multiple-spin interactions in frustrated Kondo lattice models stabilize spin scalar chiral order, revealing a novel mechanism linked to higher-order perturbations and degeneracy effects.

Contribution

It demonstrates that positive biquadratic interactions, enhanced by fourth-order perturbations, are key to stabilizing spin scalar chiral order in frustrated Kondo lattice models.

Findings

Positive biquadratic interaction is critically enhanced near 1/4 filling.

The mechanism involves a generalized Kohn anomaly due to degeneracy.

Unusual magnetic orders can emerge from this kinetic-driven interaction.

Abstract

We reveal the significance of kinetic-driven multiple-spin interactions hidden in geometrically-frustrated Kondo lattice models. Carefully examining the perturbation in terms of the spin-charge coupling up to the fourth order, we find that a positive biquadratic interaction is critically enhanced and plays a crucial role on stabilizing a spin scalar chiral order near 1/4 filling in a triangular lattice case. This is a generalized Kohn anomaly, appearing only when the second-order perturbation is inefficient because of the degeneracy under frustration. The mechanism is potentially common to frustrated spin-charge coupled systems, leading to emergence of unusual magnetic orders.