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arXiv · 2003.00626

Nanometric square skyrmion lattice in a centrosymmetric tetragonal magnet

N. D. Khanh·T. Nakajima·X. Z. Yu·S. Gao·K. Shibata·M. Hirschberger·Y. Yamasaki·H. Sagayama·H. Nakao·L. C. Peng·K. Nakajima·R. Takagi·T. Arima·Y. Tokura·S. Seki
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Abstract

Magnetic skyrmions are topologically stable spin swirls with particle-like character and potentially suitable for the design of high-density information bits. While most known skyrmion systems arise in noncentrosymmetric systems with Dzyaloshinskii-Moriya interaction, also centrosymmetric magnets with a triangular lattice can give rise to skyrmion formation, with geometrically-frustrated lattice being considered essential in this case. Until today, it remains an open question if skyrmions can also exist in the absence of both geometrically-frustrated lattice and inversion symmetry breaking. Here, we discover a square skyrmion lattice state with 1.9 nm diameter skyrmions in the centrosymmetric tetragonal magnet GdRu2Si2 without geometrically-frustrated lattice by means of resonant X-ray scattering and Lorentz transmission electron microscopy experiments. A plausible origin of the observed skyrmion formation is four-spin interactions mediated by itinerant electrons in the presence of easy-axis anisotropy. Our results suggest that rare-earth intermetallics with highly-symmetric crystal lattices may ubiquitously host nanometric skyrmions of exotic origins.

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N. D. Khanh, T. Nakajima, X. Z. Yu, S. Gao, K. Shibata, M. Hirschberger, Y. Yamasaki, H. Sagayama, H. Nakao, L. C. Peng, K. Nakajima, R. Takagi, T. Arima, Y. Tokura, S. Seki. 2020-03-02. Nanometric square skyrmion lattice in a centrosymmetric tetragonal magnet. https://doi.org/10.1038/s41565-020-0684-7

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