Modulation of skyrmion helicity by competition between Dzyaloshinskii-Moriya interaction and magnetic frustration
Yuheng Liu, Baishun Yang, Xiaoyan Guo, Silvia Picozzi, Yu Yan
Abstract
Helicity, one of the degrees of freedom for skyrmions, describing the direction of spin rotation in skyrmions, is of fundamental importance for skyrmion-based potential applications. However, continuously modulating the helicity is challenging. Here, we propose an effective method to control the skyrmion helicity by means of the competition between Dzyaloshinskii-Moriya interaction and exchange frustration in inversion-symmetry-broken frustrated magnets. In the prototypical case of Janus NiClBr, we found a nanometer-sized skyrmion with uniform unconventional helicity of ${139}^{\ensuremath{\circ}}$. Moreover, a spin texture phase diagram as a function of strain and out-of-plane magnetic field was illustrated and, most importantly, an unexpected linear change in the helicity from $\ensuremath{\sim}{0}^{\ensuremath{\circ}}$ to $\ensuremath{\sim}{50}^{\ensuremath{\circ}}$ and from $\ensuremath{\sim}{120}^{\ensuremath{\circ}}$ to $\ensuremath{\sim}{180}^{\ensuremath{\circ}}$ was found in the skyrmion lattice region. As such, the skyrmion Hall effect of Janus NiClBr can be reduced under external field for a critical value of the helicity. These results not only give a feasible method to effectively modulating the skyrmion helicity, but also provide an ideal platform for further investigations on skyrmion helicity-related phenomena.