2014/06/30 by Shi-Zeng Lin, Avadh Saxena, Cristian D. Batista · 2 citations
Physics and Astronomy · #cond-mat.mes-hall #cond-mat.mtrl-sci #nlin.PS
paper · pdf · doi:10.1103/physrevb.91.224407
published as Phys. Rev. B 91, 224407 (2015) · 7.1 pages, 7 figures
arxiv created 2015/06/05 · arxiv updated 2015/06/08
We study the equilibrium phase diagram of ultrathin chiral magnets with easy-plane anisotropy A. The vast triangular skyrmion lattice phase that is stabilized by an external magnetic field evolves continuously as a function of increasing A into a regime in which nearest-neighbor skyrmions start overlapping with each other. This overlap leads to a continuous reduction of the skyrmion number from its quantized value Q=1 and to the emergence of antivortices at the center of the triangles formed by nearest-neighbor skyrmions. The antivortices also carry a small "skyrmion number" QA ≪ 1 that grows as a function of increasing A. The system undergoes a first order phase transition into a square vortex-antivortex lattice at a critical value of A. Finally, a canted ferromagnetic state becomes stable through another first order transition for a large enough anisotropy A. Interestingly enough, this first order transition is accompanied by \it metastable meron solutions.