Multi-component quantum gases in spin-dependent hexagonal lattices

In solid-state materials, the static and dynamic properties as well as the magnetic and electronic characteristics are crucially influenced by the crystal symmetry. Hexagonal structures play a particularly important role and lead to novel physics, such as that of carbon nanotubes or graphene. Here we report on the realization of ultracold atoms in a spin-dependent optical lattice with hexagonal symmetry. We show how the combined effects of the lattice and interactions between atoms lead to a forced antiferromagnetic Néel order when two spin-components localize at different lattice sites. We also demonstrate that the coexistence of two components-one Mott-insulating and the other one superfluid-leads to an interaction-induced modulation of the superfluid density, which is observed spectroscopically. Our studies reveal the vast impact of the interaction-induced modulation on the superfluid-to-Mott- insulator transition. The observations are consistent with theoretical predictions using Gutzwiller mean-field theory.