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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)

Europe/Stockholm
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Description
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).
slides