Quantum insulating states of F=2 cold atoms in optical lattices

TL;DR

This paper explores various spin-correlated insulating states of F=2 cold atoms in optical lattices, revealing complex spin interactions and phase diagrams including dimer, trimer, and various spin-ordered Mott insulators.

Contribution

It introduces the concept of octopole spin exchange interactions and characterizes multiple novel insulating phases in F=2 cold atom systems.

Findings

Identification of octopole coupling in spin exchange interactions

Existence of multiple insulating phases including dimer, trimer, and spin-ordered states

Estimation of phase boundaries for different atom occupancies

Abstract

In this Letter we study various spin correlated insulating states of F=2 cold atoms in optical lattices. We find that the effective spin exchange interaction due to virtual hopping contains an {\em octopole} coupling between two neighboring lattice sites. Depending on scattering lengths and numbers of particles per site the ground states are either rotationally invariant dimer or trimer Mott insulators or insulating states with various spin orders. Three spin ordered insulating phases are ferromagnetic, cyclic and nematic Mott insulators. We estimate the phase boundaries for states with different numbers of atoms per lattice site.