Helicity Unification by Triangular Skyrmion Lattice Formation in the Noncentrosymmetric Tetragonal Magnet EuNiGe<sub>3</sub>
Takeshi Matsumura, Kenshin Kurauchi, Mitsuru Tsukagoshi, Nonoka Higa, Hironori Nakao, Masashi Kakihana, Masato Hedo, Takao Nakama, Yoshichika Ōnuki
Abstract
Magnetic skyrmions are particle-like spin-swirling objects ubiquitously realized in magnets.They are topologically stable chiral kinks composed of multiple modulation waves of spiral spin structures, where the helicity of each spiral is usually selected by antisymmetric exchange interactions in noncentrosymmetric crystals.We report an experimental observation of a distorted triangular lattice of skyrmions in the polar tetragonal magnet EuNiGe3, reflecting a strong coupling with the lattice.Moreover, through resonant x-ray diffraction, we find that the magnetic helicity of the original spiral at zero field is reversed when the skyrmion lattice is formed in a magnetic field.This means that the energy gain provided by the skyrmion lattice formation is larger than the antisymmetric exchange interaction.Our findings will lead us to a further understanding of emergent magnetic states.