Spectroscopic-imaging STM measurement of magnetic skyrmions in a centrosymmetric crystal*

The magnetic skyrmion, vortex-like magnetic swirling structure, has attracted attention as a topological quasi-particle. The Dzyaloshinskii-Moriya interaction originating from broken inversion symmetry in the crystal structure is considered to be the key to stabilize the skyrmion. However, a mechanism to stabilize magnetic skyrmions even in centrosymmetric crystals has been proposed [1, 2]. For such centrosymmetric systems, experiments to show how the itenerant electrons interact with the magnetic structure are highly desired for further understanding.
We performed spectroscopic-imaging scanning tunneling microscopy (SI-STM) measurements for a centrosymmetric crystal GdRu₂Si₂, which is expected to host magnetic skyrmions. As a result, we found that the density of states near the Fermi energy (0.1 eV) varies in different magnetic phases including the skyrmion phase. Besides, we also observed periodic modulation in the electronic states with the same period as the magnetic skyrmion.
In the presentation, we will discuss a possible skyrmion formation mediated by itenerant electrons.
[1] S. Hayami, R. Ozawa, and Y. Motome, Phys. Rev. B 95, 224424 (2017).
[2] R. Ozawa, S. Hayami, and Y. Motome, Phys. Rev. Lett. 118, 147205 (2017).