We propose a scheme to realize the itinerant ferromagnetism of two-component cold fermionic atoms in the $p$ -orbital bands in optical lattices. The band flatness in the two-dimensional honeycomb lattice dramatically amplifies the interaction effect, driving the ferromagnetic transition even with a relatively weak repulsive interaction. This scheme has the advantage that the stability of the system can be maintained without causing decay to the molecular state as one approaches the Feshbach resonance from the side with the positive scattering length. Experimental signatures and detections are also discussed.We propose a scheme to realize the itinerant ferromagnetism of two-component cold fermionic atoms in the $p$-orbital bands in optical lattices. The band flatness in the two-dimensional honeycomb lattice dramatically amplifies the interaction effect, driving the ferromagnetic transition even with a relatively weak repulsive interaction. This scheme has the advantage that the stability of the system can be maintained without causing decay to the molecular state as one approaches the Feshbach resonance from the side with the positive scattering length. Experimental signatures and detections are also discussed.

arXiv:0805.3031Physical Review ANov 17, 201085 citations

A Model of Itinerant Ferromagnetism in Two- and Three- Dimensional Multi-orbital Systems

Yi Li, Élliott H. Lieb, Congjun Wu

We study itinerant ferromagnetism in multi-orbital Hubbard models in certain two-dimensional square and three-dimensional cubic lattices. In the strong coupling limit where doubly occupied orbitals are not allowed we prove that the fully spin-polarized states are the unique ground states, apart from the trivial spin degeneracies, for any generic filling factor 0 < n < 2 (0 < n < 3) in two (three) dimensions. Possible applications to p-orbital bands with ultra-cold fermions in optical lattices are discussed.We study itinerant ferromagnetism in multi-orbital Hubbard models in certain two-dimensional square and three-dimensional cubic lattices. In the strong coupling limit where doubly occupied orbitals are not allowed we prove that the fully spin-polarized states are the unique ground states, apart from the trivial spin degeneracies, for any generic filling factor 0 < n < 2 (0 < n < 3) in two (three) dimensions. Possible applications to p-orbital bands with ultra-cold fermions in optical lattices are discussed.

Oct 16, 20130 citations

Quantum magnetism with ultracold fermions in an optical lattice

Daniel Greif

Bulletin of the American Physical SocietyJan 1, 20133 citations

Magnetism of cold fermionic atoms on the p band of an optical lattice

Lei Wang, Xi Dai, Shu Chen +1 more

We carry out ab initio study of a ground state phase diagram of spin- $1∕2$ cold fermionic atoms within a twofold degenerate $p$ band of an anisotropic optical lattice. Using the Gutzwiller variational approach, we show that a robust ferromagnetic phase exists for a vast range of band fillings and interacting strengths. The ground state crosses over from a spin density wave state to a spin-1 Neel state at half filling. An additional harmonic trap will induce spatial separation of various phases. We also discuss several relevant observable consequences and detection methods. An experimental test of the results reported here may shed some light on the long-standing issue of itinerant ferromagnetism.We carry out ab initio study of a ground state phase diagram of spin-$1∕2$ cold fermionic atoms within a twofold degenerate $p$ band of an anisotropic optical lattice. Using the Gutzwiller variational approach, we show that a robust ferromagnetic phase exists for a vast range of band fillings and interacting strengths. The ground state crosses over from a spin density wave state to a spin-1 Neel state at half filling. An additional harmonic trap will induce spatial separation of various phases. We also discuss several relevant observable consequences and detection methods. An experimental test of the results reported here may shed some light on the long-standing issue of itinerant ferromagnetism.

arXiv:0805.2719Physical Review AAug 4, 200817 citations

We propose a scheme to realize the itinerant ferromagnetism of two-component cold fermionic atoms in the

p

-orbital bands in optical lattices. The band flatness in the two-dimensional honeycomb lattice dramatically amplifies the interaction effect, driving the ferromagnetic transition even with a relatively weak repulsive interaction. This scheme has the advantage that the stability of the system can be maintained without causing decay to the molecular state as one approaches the Feshbach resonance from the side with the positive scattering length. Experimental signatures and detections are also discussed.

We carry out ab initio study of a ground state phase diagram of spin-

1∕2

cold fermionic atoms within a twofold degenerate

p

band of an anisotropic optical lattice. Using the Gutzwiller variational approach, we show that a robust ferromagnetic phase exists for a vast range of band fillings and interacting strengths. The ground state crosses over from a spin density wave state to a spin-1 Neel state at half filling. An additional harmonic trap will induce spatial separation of various phases. We also discuss several relevant observable consequences and detection methods. An experimental test of the results reported here may shed some light on the long-standing issue of itinerant ferromagnetism.