SKM 2021 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 27: Topological Insulators and Semimetals (joint session TT/KFM)

TT 27.8: Vortrag

Freitag, 1. Oktober 2021, 12:00–12:15, H7

2D-Berry-curvature-driven large anomalous Hall effect in layered topological nodal-line MnAlGe — •Satya N. Guin and Claudia Felser — Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany

Topological magnets comprising two-dimensional (2D) magnetic layers with Curie temperatures (TC) exceeding room temperature are key for dissipationless quantum transport devices. However, the identification of a material with 2D ferromagnetic planes that exhibits an out-of-plane-magnetization remains a challenge. We report a ferromagnetic, topological, nodal-line, and semimetal MnAlGe composed of square-net Mn layers that are separated by nonmagnetic Al-Ge spacers. The 2D ferromagnetic Mn-layers exhibit an out-of-plane magnetization below TC  503 K. Density functional calculations demonstrate that 2D arrays of Mn atoms control the electrical, magnetic, and therefore topological properties in MnAlGe. The unique 2D distribution of the Berry curvature resembles the 2D Fermi surface of the bands that formed the topological nodal line near the Fermi energy. A large anomalous Hall conductivity (AHC) of  700 S/cm is obtained at 2 K and related to this nodal line-induced 2D Berry curvature distribution. The high transition temperature, large anisotropic out-of-plane magnetism, and natural hetero-structure-type atomic arrangements consisting of magnetic Mn and non-magnetic Al/Ge elements render nodal-line MnAlGe one of the few, unique, and layered topological ferromagnets that have ever been observed.
[1] S. N. Guin et al., Adv. Mater. 2021, 33 (21), 2006301