Berlin 2018 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 50: Soft and hard permanent magnets

MA 50.5: Vortrag

Donnerstag, 15. März 2018, 16:00–16:15, EB 301

Noncollinear magnetism in Mn₃X (X=Sn, Ge, Ga) compounds — •Bendegúz Nyári, András Deák, and László Szunyogh — Budapest University of Technology and Economics, Budapest, Hungary

The intermetallic compounds Mn₃X (X=Sn, Ge, Ga) in hexagonal crystal structure show complex magnetic behaviour. Neutron diffraction [1] and theoretical [2] studies reveal that these compounds have a triangular spin configuration displaying weak ferromagnetic deformation. In a recent theoretical work [3] nonplanar spin-configurations were also reported. In this work we investigate theoretically the formation of non-collinear spin configurations. Spin-model parameters were obtained from a spin-cluster expansion (SCE) technique and by fitting rotational energies to analytic expressions derived from group-theoretical arguments. A model based on six magnetic sublattices confirms indeed a planar weak ferromagnetic ground state. In case of Mn₃Ge, the investigation of the static spin-susceptibilty, χ(q), indicates, however, that the system can be stabilized in a complicated magnetic structure at finite wavevector q. By using tensorial spin-interactions obtained from SCE, Monte-Carlo simulations are performed to study such complex magnetic ground states.

[1] S. Tomiyoshi et al., J. Magn. Magn. Mater. 54–57, 1001 (1986)

[2] L. M. Sandratskii and J. Kübler, Phys. Rev. Lett. 76, 4963 (1996)

[3] J. Kübler and C. Felser, Europhysics Lett. 108, 67001 (2014)