Skyrmion crystal formation and temperature–magnetic-field phase diagram of the frustrated triangular lattice Heisenberg magnet with easy-axis magnetic anisotropy

The nature of the skyrmion-crystal (SkX) formation and various multiple-q phases encompassing the SkX phase are investigated by extensive Monte Carlo simulations on the frustrated J₁-J₃ triangular-lattice Heisenberg model with the weak easy-axis magnetic anisotropy. Phase diagrams in the temperature T vs magnetic-field H plane are constructed, leading to a rich variety of multiple-q phases. The anisotropy stabilizes the SkX state down to $T=0$ at intermediate fields, while in the lower-field range the SkX state becomes only metastable, and new multiple-q states with a broken C₃ symmetry are instead stabilized. Implications to experiments are discussed.