Dr. Sándor Bordács (Budapest University of Technology and Economics)

Néel-type skyrmions with ferroelectric dressing

In the nature two basic types of magnetic skyrmion lattices (SkL) – periodic arrays of nanoscale spin vortices – can exist. The Bloch-type SkL can be viewed as a superposition of spin helices, where spins whirl around the vortex cores. In contrast a Néel SkL is formed by spin cycloids and a hedgehog-like spin texture is realized in each unit cell. Although early theoretical works predicted that polar crystals could be ideal hosts of SkL structures, only the Bloch-type SkL has been observed in chiral materials so far.

Based on the results of magnetization measurements, magnetic force microscopy and small-angle neutron scattering, here, we report the first observation of a SkL in the polar magnetic semiconductor GaV4S8 with rhombohedral (C3v) symmetry [1]. The SkL phase exists over an unusually broad temperature range compared with other bulk crystals. Moreover, unlike in chiral magnets the orientation of the vortices is locked to the magnetic easy axis. This may facilitate a unique magnetic control of the SkL, since we expect that the SkL induced by a magnetic field parallel to the easy axis can be rotated within the hard plane by an additional transverse field component. Supporting theory attributes the experimental findings to a new Néel-type of SkL.

[1] I. Kézsmárki, S. Bordács et. al. Nature Materials (accepted)

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