Observation of Robust Néel Skyrmions in Metallic PtMnGa

Bloch[1] and anti-skyrmions[2] have attracted much attention since their first observation. Bulk Néel skyrmions have been observed in two compounds, GaV4S8[3] and VOSe2O5[4], but at low temperatures only. Here we report the first observation of bulk Néel skyrmions in a non-centrosymmetric metallic compound PtMnGa by means of Lorentz Transmission Electron Microscopy (LTEM)[5]. Skyrmions in PtMnGa are found to be stable over a wide temperature range up to its Curie temperature (~220K). By contrast with skyrmions observed to date, we find that the skyrmion size in PtMnGa is strongly influenced by the thickness of the lamella in which the skyrmions are observed. Their size increases by a factor of 7 when the thickness is increased from ~90 nm to ~4 µm. Moreover, skyrmions can be stabilized at zero field after suitable field cooling processes and are highly robust against large in-plane magnetic fields (~1 T). These properties make PtMnGa and related compounds an extremely exciting system for future spintronic applications.

1. Yu, X.Z., et al., Nature Materials, 2010. 10
2. Nayak, A.K., et al., Nature, 2017. 548(7669)
3. Kezsmarki, I., et al., Nat Mater, 2015. 14(11)
4. Kurumaji, T., et al., Phys Rev Lett, 2017. 119(23)
5. Srivastava, A.K. et al., (under consideration)