Ferromagnetism in a lattice of Bose-Einstein condensates

Based on recent measurements of the scattering length of spin-changing collisions, it was established that the ground state of optically trapped ⁸⁷Rb spinor Bose condensates is ferromagnetic. The present study shows that this result, combined with the recent experimental realization of regular arrays of Bose-Einstein condensates in optical lattices, leads to a situation where it becomes possible to carry out detailed static and dynamic studies of magnetism on one- to three-dimensional periodic lattices. It is shown that spinor condensates undergo a ferromagneticlike phase transition that leads to a "macroscopic" magnetization of the condensate array.