*

Magnetic skyrmions have been considered to be stabilized by the Dzyloshinskii-Moriya interaction originating from inversion-symmetry breaking structures. Recently, however, magnetic skyrmion lattices have been reported in inversion-symmetric Gd based compounds [1]. These skyrmion lattices are proposed to be stabilized by multiple-spin interactions, which are mediated by itinerant electrons [2-4].
We performed spectroscopic-imaging scanning tunneling microscopy experiments on GdRu₂Si₂ to investigate the nature of the coupling between itinerant electrons and localized magnetic moments. It revealed that the local density of states near the Fermi energy (~ 0.1 eV) shows characteristic spatial patterns in accordance with the magnetic structures. The patterns are well reproduced by charge-density distributions calculated based on the multiple-spin interaction and the exchange coupling between itinerant electrons and Gd local moments.
[1] N. D. Khanh et al., Nat. Nanotechnol. 15, 444 (2020).
[2] R. Ozawa, S. Hayami, and Y. Motome, Phys. Rev. Lett. 118, 147205 (2017).
[3] S. Hayami, R. Ozawa, and Y. Motome, Phys. Rev. B 95, 224424 (2017).
[4] T. Nomoto, T. Koretsune, and R. Arita, Phys. Rev. Lett. 125, 117204 (2020).