Tailoring Magnetic Skyrmions by Geometric Confinement of Magnetic Structures*

There is growing interest in systems that can host magnetic skyrmions at room temperature (RT) without Dzyaloshinskii-Moriya interaction (DMI), which enable novel ways to manipulate properties of skyrmions. In this work [1], we show theoretically that, in ferromagnetic thin films with inverse symmetry, skyrmion lattices (SkX) can be stabilized by spatially varying uniaxial magnetic anisotropy with easy axis periodically rotating from in-plane to out-of-plane. Phase diagrams in the plane of magnetic field and temperature were calculated by using a Ginzburg-Landau approach, which demonstrate that SkX is energetically favorable at RT with small magnetic field of the order of 10 Oe. Remarkably, the size of the skyrmions is determined by the ratio of the exchange length and the period of the spatial modulation of the anisotropy, at variance with those stabilized by dipolar interaction and DMI. We will also apply our theory to centrosymmetric multiferroics where SkXs were recently observed at RT.
[1] Zhang, Phatak, Petford-Long and Heinonen, arXiv:1710.00048.