Metallic magnetization plateau on triangular lattice

The $1/3$ magnetization plateau is well established for spin $1/2$ Heisenberg antiferromagnetic model on triangular lattice. The state is stable against a large range of spatial anisotropies and is observed in the triangular compound Cs$_2$CuBr$_4$. A natural question to ask is whether the plateau state remains stable if the on-site repulsion $U$ is lowered for the underlying Hubbard model. In our work, we studied the one-band Hubbard model on triangular lattice. Through mean-field calculations, it is discovered that an up-up-down spin density wave state with $1/3$ of saturation magnetization is stablized for a range of $U$ and magnetic field $h$. For $4.44t\le U\le 4.55t$, the state is a half metal: the spin up bands remain metallic while the spin down bands are insulating. For $U> 4.55t$, the spin up bands become gapped and the system is an insulator. It is speculated the plateau state remains stable for the entire range of $U\ge 4.44t$.