Phase Diagram of the Two-Leg Kondo Ladder

TL;DR

This study maps the phase diagram of the two-leg Kondo ladder, revealing ferromagnetic, paramagnetic, and dimerized phases, with insights into spin and charge behaviors across different electron densities and coupling strengths.

Contribution

It provides the first detailed computational phase diagram of the two-leg Kondo ladder, identifying various magnetic and charge phases and their dependence on electron density and Kondo coupling.

Findings

Ferromagnetism occurs at low electron densities and strong Kondo coupling.

Paramagnetic phase dominates at higher densities ($n geq 0.4$) regardless of coupling.

Spin dimerization is observed at specific densities ($n=1/4$ and $n=1/2$).

Abstract

The phase diagram of the two-leg Kondo ladder is investigated using computational techniques. Ferromagnetism is present, but only at small conduction electron densities and robust Kondo coupling $J$. For densities $n\gtrsim0.4$ and any Kondo coupling, a paramagnetic phase is found. We also observed spin dimerization at densities $n$=1/4 and $n$=1/2. The spin structure factor at small $J$ peaks at $\vec{q}$=$(2n,0)\pi$ for $n\lesssim0.5$, and at $\vec{q}$=$(n,1)\pi$ for $n\gtrsim0.5$. The charge structure factor suggests that electrons behave as free particles with spin-1/2 (spin-0) for small (large) $J$.