title: Dimerized solids and resonating plaquette order in SU(N)-Dirac fermions.
abstract: We study the quantum phases of fermions with an explicit SU(N)-symmetric, Heisenberg-like nearest-neighbor flavor exchange interaction on the honeycomb lattice at half filling. Employing projective (zero temperature) quantum Monte Carlo simulations for even values of N, we explore the evolution from a weak-coupling semimetal into the strong-coupling, insulating regime. Furthermore, we compare our numerical results to a saddle-point approximation in the large-N limit. From the large-N regime down to the SU(6) case, the insulating state is found to be a columnar valence bond crystal, with a direct transition to the semimetal at weak, finite coupling, in agreement with the mean-field result in the large-N limit. At SU(4) however, the insulator exhibits a subtly different valence bond crystal structure, stabilized by resonating valence bond plaquettes. In the SU(2) limit, our results support a direct transition between the semimetal and an antiferromagnetic insulator.
authors: Department of Physics, Boston University, Boston, Massachusetts 02215, USA. tcl@bu.edu
authors: Thomas C
authors: TC
authors: Lang
authors: Zi Yang
authors: ZY
authors: Meng
authors: Alejandro
authors: A
authors: Muramatsu
authors: Stefan
authors: S
authors: Wessel
authors: Fakher F
authors: FF
authors: Assaad