title: π phases in balanced fermionic superfluids on spin-dependent optical lattices.
abstract: We study a balanced two-component system of ultracold fermions in one dimension with attractive interactions and subject to a spin-dependent optical lattice potential of opposite sign for the two components. We find states with different types of modulated pairing order parameters which are conceptually similar to π phases discussed for superconductor-ferromagnet heterostructures. Increasing the lattice depth induces sharp transitions between states of different parity. While the origin of the order parameter oscillations is similar to the Fulde-Ferrel-Larkin-Ovchinnikov phase for paired states with spin imbalance, the current system is intrinsically stable to phase separation. We discuss experimental requirements for creating and probing these novel phases.
authors.affiliation: Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Zapata
authors.forename: B
authors.initials: B
authors.lastname: Wunsch
authors.forename: N T
authors.initials: NT
authors.lastname: Zinner
authors.forename: E
authors.initials: E
authors.lastname: Demler