Polarized neutron scattering study of the centrosymmetric skyrmion host material Gd2PdSi3

We investigated magnetic structures of the centrosymmetric skyrmion material ${\mathrm{Gd}}₂{\mathrm{PdSi}}₃$ by means of polarized neutron scattering near zero field with an isotope-$¹⁶⁰\mathrm{Gd}$-enriched single crystal. In a previous study, magnetic structures in ${\mathrm{Gd}}₂{\mathrm{PdSi}}₃$ at low temperatures were studied by resonant x-ray scattering measurements [T. Kurumaji et al., Science 365, 914 (2019)]. The present polarized neutron results confirm that the magnetic structure in zero field has elliptic screw-type magnetic modulation with a propagation vector of $(q,0,0)$ with $q\ensuremath{\sim}0.14$ and its equivalents. As the temperature increases, the system undergoes a magnetic phase transition while keeping the incommensurate $q$-vector of $(q,0,0)$. We found that the thermally induced phase has sinusoidal magnetic modulations with magnetic moments perpendicular both to the $c$ axis and to the $\mathbit{q}$-vector. We also investigate the spin-helicity degree of freedom in the ground state by polarized neutrons, revealing that the system contains equal fractions of the left-handed and right-handed screw-type orders as expected from the centrosymmetric crystal structure.