Regensburg 2019 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 9: Cooperative phenomena: Spin structures and magnetic phase transitions
MA 9.3: Vortrag
Montag, 1. April 2019, 15:30–15:45, H53
Weak ferromagnetism in Mn3X (X=Sn, Ge, Ga) compounds — •Bendegúz Nyári1, András Deák1,2, Jerome Jackson3, and László Szunyogh1,2 — 1Budapest University of Technology and Economics, Budapest, Hungary — 2MTA-BME Condensed Matter Research Group, Budapest, Hungary — 3STFC Scientific Computing Department, Warrington, UK
The intermetallic compounds Mn3X (X=Sn, Ge, Ga) in hexagonal crystal structure show complex magnetic behavior. Neutron diffraction [1] and theoretical [2,3] studies reveal that these compounds have a triangular spin configuration displaying weak ferromagnetic deformation. In this work, we investigate theoretically the noncollinear magnetic structures of these compounds. Spin model parameters are obtained by using a spin-cluster expansion (SCE) technique. A model based on three magnetic sublattices allows both a group theoretical analysis and also a quantitative description of weak ferromagnetism. We also perform unconstrained and constrained LSDA calculations, where we focused on exploring the effect of spin-orbit coupling and induced moments. In case of Mn3Sn, neutron diffraction experiments also reveal a helical modulation of the weak-ferromagnetic state along the z-axis not yet explained theoretically. We present detailed investigations on how these helical states appear in the isotropic Heisenberg model.
[1] S. Tomiyoshi et al., J. Magn. Mater. 54–57, 1001 (1986)
[2] L. M. Sandratskii and J. Kübler, Phys. Rev. Lett. 76, 4963 (1996)
[3] D. Zhang et al. J. Phys.: Condens. Matter 25 (2013)