Pi-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 pi-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 FFLO 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.

4.3 pages, 4 figures, published version

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• Observation of Phase Separation in a Strongly-Interacting Imbalanced Fermi Gas
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• Direct Observation of the Superfluid Phase Transition in Ultracold Fermi Gases
• Striped superconductors: How the cuprates intertwine spin, charge and superconducting orders
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• Creating State-Dependent Lattices for Ultracold Fermions by Magnetic Gradient Modulation
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• Detecting $\pi$-phase superfluids with $p$-wave symmetry in a quasi-1D optical lattice
• Interplay of Superconductivity and Spin-Dependent Disorder
• Generating an effective magnetic lattice for cold atoms
• Mobile magnetic impurities in a Fermi superfluid: a route to designer molecules
• Component separation of two-component fermion clouds in a spin-dependent external potential by spin-density-functional theory
• Topological transitions of gapless paired states in mixed-geometry lattices
• Triplet pair correlations in {\it s-}wave superfluids as a signature of the FFLO state
• Unconventional pairing in few-fermion systems at finite temperature
• Few-body perspective on fermionic pairing in one spatial dimension
• Fulde-Ferrell superfluids in spinless ultracold Fermi gases
• Unconventional pairing in few-fermion systems tuned by external confinement