Magnetic phases of two-component lattice bosons at nonzero temperature

Barbara Capogrosso-Sansone, Marco Guglielmino, Vittorio Penna

Yariv Yanay, Erich J. Mueller, Veit Elser

We use a high-temperature expansion to explore spin correlations around a single hole in a two-dimensional lattice filled with a hard-core two-component bose gas. We find that the spins around the hole develop ferromagnetic order and quantify the degree of polarization at temperatures of the order of the hopping energy, finding a measurably nonzero polarization. We also discuss the effect of fixing the overall magnetization of the system for finite-sized systems.

Andreas Hubener, Michiel Snoek, Walter Hofstetter

We investigate spin-order of ultracold bosons in an optical lattice by means of dynamical mean-field theory. A rich phase diagram with anisotropic magnetic order is found, both for the ground state and at finite temperatures. Within the Mott insulator, a ferromagnetic to antiferromagnetic transition can be tuned using a spin-dependent optical lattice. In addition we find a supersolid phase, in which superfluidity coexists with antiferromagnetic spin order. We present detailed phase diagrams at finite temperature for the experimentally realized heteronuclear $^{87}\text{R}\text{b-}^{41}\text{K}$ mixture in a three-dimensional optical lattice.

Alvaro Caramico D’Auria, L. De Cesare, Ileana Rabuffo

Kenichi Kasamatsu, Y. Nakano, Tetsuo Matsui

Yongqiang Li, M. Reza Bakhtiari, Liang He +1 more

We theoretically address magnetic ordering at zero and finite temperature in both homogeneous and trapped Bose-Bose mixtures in optical lattices. By using bosonic dynamical mean-field theory, we obtain the phase diagram of the homogeneous two-component Bose-Hubbard model in a three-dimensional cubic lattice, which features competing magnetic order of $XY$ ferromagnetic and antiferromagnetic type in addition to the Mott and superfluid states. We show that these magnetic phases persist also in the presence of a harmonic trap.