Magnetism Of Spinor Alkali-Metal And Alkaline-Earth-Metal Atoms In Optical Lattices

We theoretically investigate zero-temperature magnetic ordering of mixtures of spin-1 (alkali-metal atoms) and spin-0 (alkaline-earth-metal atoms) bosons in a three-dimensional optical lattice. With the single-mode approximation for the spin-1 bosons, we obtain an effective Bose-Hubbard model for describing the heteronuclear mixtures in optical lattices. By controlling the interspecies interactions between alkali-metal and alkaline-earth-metal atoms, we map out complete phase diagrams of the system with both positive and negative spin-dependent interactions for spin-1 atoms, based on bosonic dynamical mean-field theory. We find that the spin-1 components feature ferromagnetic and nematic insulating phases, in addition to the superfluid, depending on spin-dependent interactions. Take the spin-1 alkali-metal bosons as spin up arrow, and spin-0 alkaline-earth-metal bosons as spin down arrow, we observe that the system favors ferromagnetic insulator at filling n = 1 and unorder insulator at n = 2. Interestingly, we observe a two-step Mott-insulating-superfluid phase transition, as a result of mass imbalance between alkali-metal and alkaline-earth-metal atoms.