SciPost Phys. 5, 063 (2018) ·
published 18 December 2018
|
· pdf
Mn$_{3}$X (X= Sn, Ge) are noncollinear antiferromagnets hosting a large
anomalous Hall effect (AHE). Weyl nodes in the electronic dispersions are
believed to cause this AHE, but their locus in the momentum space is yet to be
pinned down. We present a detailed study of the Hall conductivity tensor and
magnetization in Mn$_{3}$Sn crystals and find that in the presence of a
moderate magnetic field, spin texture sets the orientation of the $k$-space
Berry curvature with no detectable in-plane anisotropy due to the $Z_6$
symmetry of the underlying lattice. We quantify the energy cost of domain
nucleation and show that themultidomain regime is restricted to a narrow field
window. Comparing the field dependence of AHE and magnetization, we find that
there is a distinct component in the AHE which does not scale with
magnetization when the domain walls are erected. This so-called `topological'
Hall effect provides indirect evidence for a non-coplanar spin components and
real-space Berry curvature in domain walls.
