Abstract
We theoretically investigate a new stabilization mechanism of a skyrmion crystal (SkX) in centrosymmetric itinerant magnets with magnetic anisotropy. By considering a trigonal crystal system without the horizontal mirror plane, we derive an effective spin model with an anisotropic Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction for a multi-band periodic Anderson model. We find that the anisotropic RKKY interaction gives rise to two distinct SkXs with different skyrmion numbers of one and two depending on a magnetic field. We also clarify that a phase arising from the multiple-Q spin density waves becomes a control parameter for a field-induced topological phase transition between the SkXs. The mechanism will be useful not only for understanding the SkXs, such as that in Gd_2PdSi_3, but also for exploring further skyrmion-hosting materials in trigonal itinerant magnets.
Highlights
On the basis of simulated annealing and variational calculation, we show that the anisotropic RKKY interaction induces two SkXs with different topological numbers, which accompanies the spontaneous inversion symmetry breaking
Such a theoretical exploration of the SkXs based on magnetic anisotropy will be left for future study
Summary
We clarify that the magnetic anisotropy arising from the breaking of the mirror symmetry is another way to stabilize the SkXs in itinerant magnets irrespective of the spatial inversion symmetry. On the basis of simulated annealing and variational calculation, we show that the anisotropic RKKY interaction induces two SkXs with different topological numbers, which accompanies the spontaneous inversion symmetry breaking.
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