Controllable interskyrmion attractive interactions and resulting skyrmion-lattice structures in two-dimensional chiral magnets with in-plane anisotropy

We study interskyrmion interactions and stable spin configurations in a two-dimensional chiral magnet, in particular, focusing on the effects of two in-plane anisotropies: a tilted magnetic field and the magnetocrystalline anisotropy on a (011) thin film. Using analytical and micromagnetic calculations with ignoring the dipole-dipole interactions, we find that a slight deformation of a skyrmion shape makes the interskyrmion interaction anisotropic and weakly attractive. Furthermore, when the magnetocrystalline anisotropy is comparable to the Zeeman energy, skyrmions embedded in a uniform magnetization are tightly bound by creating a magnetic domain between them. The formation of the magnetic domain, and thus the strength of the interskyrmion interaction, can be controlled by the direction of an external magnetic field. The anisotropic interaction also affects the skyrmion alignment in the skyrmion crystal (SkX) phase. By employing the Monte Carlo simulation and the Landau-Lifshitz-Gilbert equation, we obtain an elongated triangular SkX phase. In particular, in the presence of a strong magnetocrystalline anisotropy, magnetic domains appear in the background of the lattice structure. We also find a parameter region that the SkX phase is stabilized due to the interskyrmion attraction.