Feasibility of Kitaev quantum spin liquids in ultracold polar molecules

TL;DR

This study investigates the potential realization of Kitaev quantum spin liquids using ultracold polar molecules, revealing challenges posed by long-range interactions that tend to induce magnetic order over spin liquid states.

Contribution

The paper analyzes the stability of the Kitaev quantum spin liquid in ultracold polar molecules with long-range interactions, highlighting the impact of interaction range on quantum spin liquid realization.

Findings

Ground state is magnetically ordered in both ferromagnetic and antiferromagnetic models.

Isotropic interactions are most frustrated and closest to a spin liquid.

Long-range interactions destroy the Kitaev quantum spin liquid.

Abstract

Ultracold atoms and molecules trapped in optical lattices are expected to serve as simulators of strongly correlated systems and topological states of matter. A fascinating example is to realize the Kitaev quantum spin liquid by using ultracold polar molecules. However, although experimental implementation of the Kitaev-type interaction was proposed, the stability of the Kitaev quantum spin liquid has not been fully investigated thus far. Here we study a quantum spin model with long-range angle-dependent Kitaev-type interactions proposed for the polar molecules, by the pseudofermion functional renormalization group method. We reveal that the ground state is magnetically ordered in both ferromagnetic and antiferromagnetic models regardless of the spatial anisotropy of the interactions, while the isotropic case is most frustrated and closest to the realization of the Kitaev quantum spin liquid. Furthermore, by introducing a cutoff in the interaction range, we clarify how the Kitaev quantum spin liquid is destroyed by the long-range interactions. The results urge us to reconsider the feasibility of the Kitaev quantum spin liquid in ultracold polar molecules.