The band structure for spin-orbit-coupled noninteracting particles on a 2D square lattice shows four degenerate minima in the lower band, due to rotational symmetry breaking by the lattice, as well as a Dirac cone.

From the article:

Bose-Hubbard Models with Synthetic Spin-Orbit Coupling: Mott Insulators, Spin Textures, and Superfluidity
William S. Cole, Shizhong Zhang, Arun Paramekanti, and Nandini Trivedi
Phys. Rev. Lett. 109, 085302 (2012)

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