Designing Quantum Spin-Orbital Liquids in Artificial Mott Insulators

TL;DR

This paper proposes creating artificial Mott insulators with Coulomb impurity lattices on gapped honeycomb substrates to simulate SU(4) symmetric spin-orbital models, potentially enabling observation of quantum spin-orbital liquids at higher temperatures.

Contribution

It introduces a method to engineer quantum spin-orbital liquids using Coulomb impurity lattices on solid-state platforms, expanding possibilities beyond cold atom systems.

Findings

Coulomb impurity lattices can simulate SU(4) symmetric models.

Antiferromagnetic correlations are driven by super-exchange interactions.

Quantum spin-orbital liquids could be realized at higher temperatures.

Abstract

Quantum spin-orbital liquids are elusive strongly correlated states of matter that emerge from quantum frustration between spin and orbital degrees of freedom. A promising route towards the observation of those states is the creation of artificial Mott insulators where antiferromagnetic correlations between spins and orbitals can be designed. We show that Coulomb impurity lattices on the surface of gapped honeycomb substrates, such as graphene on SiC, can be used to simulate SU(4) symmetric spin-orbital lattice models. We exploit the property that massive Dirac fermions form mid-gap bound states with spin and valley degeneracies in the vicinity of a Coulomb impurity. Due to electronic repulsion, the antiferromagnetic correlations of the impurity lattice are driven by a super-exchange interaction with SU(4) symmetry, which emerges from the bound states degeneracy at quarter filling. We propose that quantum spin-orbital liquids can be engineered in artificially designed solid-state systems at vastly higher temperatures than achievable in optical lattices with cold atoms. We discuss the experimental setup and possible scenarios for candidate quantum spin-liquids in Coulomb impurity lattices of various geometries.