π phases in balanced fermionic superfluids on spin-dependent optical lattices.
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.
Zapata
I
I
Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain.
Wunsch
B
B
Zinner
N T
NT
Demler
E
E