Exotic Superconducting Phases of Ultracold Atom Mixtures on Triangular Lattices

Abstract

We study the phase diagram of two-dimensional Bose-Fermi mixtures of ultracold atoms on a triangular optical lattice, in the limit when the velocity of bosonic condensate fluctuations is much larger than the Fermi velocity. We contrast this work with our previous results for a square lattice system in Phys. Rev. Lett. {\bf 97}, 030601 (2006). Using functional renormalization group techniques we show that the phase diagrams for a triangular lattice contain exotic superconducting phases. For spin-1/2 fermions on an isotropic lattice we find a competition of $s$-, $p$-, extended $d$-, and $f$-wave symmetry, as well as antiferromagnetic order. For an anisotropic lattice, we further find an extended p-wave phase. A Bose-Fermi mixture with spinless fermions on an isotropic lattice shows a competition between $p$- and $f$-wave symmetry. These phases can be traced back to the geometric shapes of the Fermi surfaces in various regimes, as well as the intrinsic frustration of a triangular lattice.

6 pages, 4 figures, extended version, slight modifications

References in corpus (5)

• Observation of Bose-Einstein Condensation of Molecules
• Spatial quantum noise interferometry in expanding ultracold atom clouds
• U(1) Gauge Theory of the Hubbard Model : Spin Liquid States and Possible Application to k-(BEDT-TTF)_2 Cu_2 (CN)_3
• Mixtures of Bosonic and Fermionic Atoms in Optical Lattices
• Renormalization Group Approach to Strong-Coupled Superconductors

Cited by in corpus (3)

• Supersolidity of cold-atom Bose-Fermi mixtures in optical lattices
• Pairing and density-wave phases in Boson-Fermion mixtures at fixed filling
• Effects of a dilute gas of fermions on the superfluid-insulator phase diagram of the Bose-Hubbard model