Fermi-surface origin of helical single Q-state and skyrmion lattice in centrosymmetric Gd compounds

Juba Bouaziz1, Eduardo M. Tapia1, Stefan Blügel1, Julie Staunton2

1Forschungszentrum Jülich, Germany
2University of Warwick, Coventry CV4 7AL, United Kingdom

We show from first principles that cylindrical structures within the Fermi surface are the origin of the single-Q helical state in the GdRu2Si2 and Gd2PdSi3 intermetallic compounds.  The geometry of the Fermi surface nesting describes the strength and sign of the underlying pairwise Ruderman-Kittel-Kasuya-Yosida interactions between the Gd moments as the main mechanism. These interactions are quasi-two-dimensional, isotropic within the Gd layers, and provide a transition temperature and helix period in very good agreement with experiment. Using atomistic spin-dynamical simulations, we investigate the effects of magnetic anisotropy and construct a general magnetic phase diagram that explains the stabilization of the 2Q skyrmion lattice observed in experiment with applied magnetic fields.

This work was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovationprogram (Grant No.\ 856538, project 3D MAGiC'),  UK EPSRC Grant No. EP/M028941/1,Deutsche Forschungsgemeinschaft (DFG) through SPP 2137 Skyrmionics (Project BL 444/16) and the Collaborative Research Centers SFB 1238 (Project C01).

Reference
[1] J. Bouaziz et al. Phys. Rev. Lett. 128, 157206 (2022).