KTH/Nordita/SU seminar in Theoretical Physics

The post-graphene era: strongly interacting Dirac fermions with cold atoms

by Cristiane Morais Smith (University of Utrecht)



Uniform magnetic fields are ubiquitous in nature, but this is not the case for staggered magnetic fields. I will discuss an experimental set-up recently proposed by us [1], which may allow for the realization of a "staggered magnetic field" in a 2D optical lattice loaded with cold atoms. If the lattice is loaded with bosons, the effective Hamiltonian of the system is a Bose-Hubbard one, with complex and anisotropic hopping coefficients. A very rich phase diagram emerges from the model: besides the usual Mott-insulator and zero-momentum condensate, a new phase with a finite momentum condensate becomes the ground-state at high-rotation [2]. An extension for fermionic atoms leads to an anisotropic Dirac spectrum, which is relevant to graphene and high-Tc superconductors [2]. When the system is loaded with a mixture of fermions and bosons, an unconventional superconducting phase may be realized [3]. [1] A. Hemmerich and C. Morais Smith, Phys. Rev. Lett. 99, 113002 (2007). [2] Lih-King Lim, A. Hemmerich, and C. Morais Smith, Phys. Rev. Lett. 100, 130402 (2008). [3] Lih-King Lim, A. Lazarides, A. Hemmerich, and C. Morais Smith, arXiv:0905.1281 (2009).