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Nanometric square skyrmion lattice in a centrosymmetric tetragonal magnet

2020; Nature Portfolio; Volume: 15; Issue: 6 Linguagem: Inglês

10.1038/s41565-020-0684-7

1748-3395

N. D. Khanh, Taro Nakajima, Xiuzhen Yu, Shang Gao, Kiyou Shibata, Max Hirschberger, Yuichi Yamasaki, Hajime Sagayama, Hironori Nakao, Licong Peng, Kiyomi Nakajima, R. Takagi, T. Arima, Yoshinori Tokura, S. Seki,

Magnetic and transport properties of perovskites and related materials

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.