Sept. 25 Club Meeting: Dr. Ziyang Meng

Paper to be discussed:

Antiferromagnetism in the Hubbard Model on the Bernal-Stacked Honeycomb Bilayer

Thomas C. Lang, Zi Yang Meng, Michael M. Scherer, Stefan Uebelacker, Fakher F. Assaad, Alejandro Muramatsu, Carsten Honerkamp, and Stefan Wessel.
Phys. Rev. Lett. 109, 126402 (2012)

Abstract:

Using a combination of quantum Monte Carlo simulations, functional renormalization group calculations and mean-field theory, we study the Hubbard model on the Bernal-stacked honeycomb bilayer at half-filling as a model system for bilayer graphene. The free bands consisting of two Fermi points with quadratic dispersions lead to a finite density of states at the Fermi level, which triggers an antiferromagnetic instability that spontaneously breaks sublattice and spin rotational symmetry once local Coulomb repulsions are introduced. Our results reveal an inhomogeneous participation of the spin moments in the ordered ground state, with enhanced moments at the threefold coordinated sites. Furthermore, we find the antiferromagnetic ground state to be robust with respect to enhanced interlayer couplings and extended Coulomb interactions.

Time: Sep 25, Tuesday, noon.

Location: Rm. 435, Nicholson Hall

Foods and drinks will be provided.