p-wave Superfluidity by Spin-Nematic Fermi Surface Deformation
  We study attractively interacting fermions on a square lattice with dispersion relations exhibiting strong spin-dependent anisotropy. The resulting Fermi surface mismatch suppresses the s-wave BCS-type instability, clearing the way for unconventional types of order. Unbiased sampling of the Feynman diagrammatic series using Diagrammatic Monte Carlo methods reveals a rich phase diagram in the regime of intermediate coupling strength. Instead of a proposed Cooper-pair Bose metal phase [A. E. Feiguin and M. P. A. Fisher, Phys. Rev. Lett. 103, 025303 (2009)] we find an incommensurate density wave at strong anisotropy and two different p-wave superfluid states with unconventional symmetry at intermediate anisotropy. 
Jan Gukelberger, Evgeny Kozik, Lode Pollet, Nikolay Prokof'ev, Manfred   Sigrist, Boris Svistunov and Matthias Troyer
cond-mat.quant-gas cond-mat.str-el cond-mat.supr-con