Spiral ferrimagnetic phases in the two-dimensional Hubbard model

• Spiral ferrimagnetic phases are studied in the 2D mean-field Hubbard model.
• The doping vs interaction (n,U)(n,U) phase diagram displays a spiral ferrimagnetic phase for intermediate U.
• For high U, non-spiral ferrimagnetic phases are found.
• Spiral ferrimagnetic phases with fixed n emerge in the chemical potential vs U phase diagram.
• The ferrimagnetic phases reflect the opening of additional energy gaps.

We address the possibility of spiral ferrimagnetic phases in the mean-field phase diagram of the two-dimensional (2D) Hubbard model. For intermediate values of the interaction U   (6≲U/t≲116≲U/t≲11) and doping n, a spiral ferrimagnetic phase is the most stable phase in the (n,U) phase diagram. Higher values of U   lead to a non-spiral ferrimagnetic phase. If phase separation is allowed and the chemical potential μμ replaces the doping n   as the independent variable, the (μ,U)(μ,U) phase diagram displays, in a considerable region, a spiral (for 6≲U/t≲116≲U/t≲11) and non-spiral (for higher values of U) ferrimagnetic phase with fixed particle density, n=0.5, reflecting the opening of an energy gap in the mean-field quasi-particle bands