Following the early prediction of the skyrmion lattice (SkL)—a periodic array of spin vortices—it has been observed recently in various magnetic crystals mostly with chiral structure. Although non-chiral but polar crystals with Cnv symmetry were identified as ideal SkL hosts in pioneering theoretical studies, this archetype of SkL has remained experimentally unexplored. Here, we report the discovery of a SkL in the polar magnetic semiconductor GaV4S8 with rhombohedral (C3v) symmetry and easy axis anisotropy. The SkL exists over an unusually broad temperature range compared with other bulk crystals and the orientation of the vortices is not controlled by the external magnetic field, but instead confined to the magnetic easy axis. Supporting theory attributes these unique features to a new Néel-type of SkL describable as a superposition of spin cycloids in contrast to the Bloch-type SkL in chiral magnets described in terms of spin helices.
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We thank H. A. K. V. Nidda and T. Fehér for useful discussions. This work was supported by the Hungarian Research Funds OTKA K 108918, OTKA PD 111756 and Bolyai 00565/14/11, by the European Research Council Project CONQUEST, by the Swiss NSF Grant Nos. 153451, 146870 and 141962, by the DFG under Grant No. SFB 1143 and via the Transregional Research Collaboration TRR 80 From Electronic Correlations to Functionality (Augsburg/Munich/Stuttgart) and by JSPS KAKENHI under Grant Nos. 25870169 and 25287088 from MEXT Japan.
The authors declare no competing financial interests.
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Kézsmárki, I., Bordács, S., Milde, P. et al. Néel-type skyrmion lattice with confined orientation in the polar magnetic semiconductor GaV4S8. Nature Mater 14, 1116–1122 (2015). https://doi.org/10.1038/nmat4402
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