Spin-orbital exchange of strongly interacting fermions on the $p$-band of a two-dimensional optical lattice

Zhenyu Zhou; Erhai Zhao; W. Vincent Liu

doi:10.1103/physrevlett.114.100406

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arXiv · 1411.4496

Spin-orbital exchange of strongly interacting fermions on the $p$-band of a two-dimensional optical lattice

Zhenyu Zhou·Erhai Zhao·W. Vincent Liu

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Abstract

Mott insulators with both spin and orbital degeneracy are pertinent to a large number of transition metal oxides. The intertwined spin and orbital fluctuations can lead to rather exotic phases such as quantum spin-orbital liquids. Here we consider two-component (spin 1/2) fermionic atoms with strong repulsive interactions on the $p$-band of the optical square lattice. We derive the spin-orbital exchange for quarter filling of the $p$-band when the density fluctuations are suppressed, and show it frustrates the development of long range spin order. Exact diagonalization indicates a spin-disordered ground state with ferro-orbital order. The system dynamically decouples into individual Heisenberg spin chains, each realizing a Luttinger liquid accessible at higher temperatures compared to atoms confined to the $s$-band.

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Zhenyu Zhou, Erhai Zhao, W. Vincent Liu. 2014-11-24. Spin-orbital exchange of strongly interacting fermions on the $p$-band of a two-dimensional optical lattice. https://doi.org/10.1103/physrevlett.114.100406

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