Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 54: Magnetic textures: Transport and dynamics III

MA 54.3: Vortrag

Freitag, 5. April 2019, 10:00–10:15, H37

Composition dependent exchange interactions and Gilbert damping in (Mn,Fe)Ge B20 alloys — •S. Mankovsky and H. Ebert — Dept. Chemistry, LMU Munich, D-81377 Munich, Germany

First-principles investigations of the magnetic properties of various materials with B20 crystal structure have been performed for different composition and structure parameters. The calculations are based on the fully relativistic multiple scattering Korringa-Kohn-Rostoker (KKR) formalism. A particular issue of these investigations is the Gilbert damping (GD) parameter and its strong dependence on the conditions of sample preparation as it was demonstrated experimentally for the FeGe compound [1]. Therefore, detailed investigations on the temperature and composition dependence of the GD have been performed for pure FeGe and MnGe compounds as well as for (Mn,Fe)Ge alloys. This study shows in particular an increase of the GD by an order of magnitude when going from MnGe to FeGe. The impact of the structure parameters and different types of defects (e.g. vacancies and antisite defects) was investigated to understand the dependence on sample preparation conditions. In addition, the exchange parameters, both isotropic and Dzyaloshinskii-Moriya interactions (DMI), have been calculated accounting simultaneously for thermal lattice vibrations and spin fluctuations, vacancies and antisite defects. From this we find in particular a significant increase of the DMI, namely diagonal D^αα elements, in the pure MnGe limit. All results are compared with available experimental data as far as possible.

[1] Phys. Rev. B 95, 134416 (2017)