First-Order Phase Transition and Anomalous Hysteresis of Binary Bose Mixtures in an Optical Lattice

We study a first-order phase transition between superfluid and Mott insulator phases in binary Bose mixtures loaded into a hypercubic optical lattice. The system is described by a two-component Bose-Hubbard model. Considering the difference between the two kinds of bosons in the intra-component interaction strength, we discuss the metastability of the system and the hysteresis associated with the first-order superfluid-Mott insulator transition. It is found that the sweeping of hopping amplitude induces a conventional hysteresis-loop behavior. We also find an anomalous hysteresis behavior when the chemical potential is varied. In the anomalous hysteresis, the phase transition occurs in a unidirectional way and a hysteresis loop does not form.