Spin Imbalance Effect in a Mixture of Spinor Fermions and Hard-Core Bosons

Mixtures of bosons and fermions have been the subject of research since the first studies of ³He-⁴He system. With the current cold atoms setups, these types of mixtures can be realized and the inter- and intraspecies interactions can be readily tuned. By means of a Bose-Fermi Hubbard Hamiltonian, mixtures of bosons and fermions can be studied theoretically. Different superfluids, Mott Insulators, phase separation, spin and charge density waves, together with Wigner crystals have been reported for these systems. We study numerically the effect that spin imbalance can have in these mixtures, specifically for a system of spinor fermions and in the hard-core bosonic limit. Using DMRG we explore the phase diagram of the ground state, finding new insulator states that appear only when there is imbalance in the system. This happens for both attractive and repulsive intraspecies interactions and for both attractive and repulsive fermionic interactions, implying that the new insulator states are due to the coupling between bosons and fermions.