Spontaneous particle-hole symmetry breaking of correlated fermions on the Lieb lattice
Spontaneous particle-hole symmetry breaking of correlated fermions on the Lieb lattice
We study spinless fermions with nearest-neighbor repulsive interactions ($t\text{\ensuremath{-}}V$ model) on the two-dimensional three-band Lieb lattice. At half-filling, the free electronic band structure consists of a flat band at zero energy and a single cone with linear dispersion. The flat band is expected to be unstable upon inclusion of electronic …