SrMnSb_22
is suggested to be a magnetic topological semimetal. It contains square,
2D Sb planes with non-symmorphic crystal symmetries that could protect
band crossings, offering the possibility of a quasi-2D, robust Dirac
semi-metal in the form of a stable, bulk (3D) crystal. Here, we report a
combined and comprehensive experimental and theoretical investigation of
the electronic structure of SrMnSb_22,
including the first ARPES data on this compound.
SrMnSb_22
possesses a small Fermi surface originating from highly 2D, sharp and
linearly dispersing bands (the ‘Y-states’) around the (0,/a)-point in
kk-space.
The ARPES Fermi surface agrees perfectly with that from bulk-sensitive
Shubnikov de Haas data from the same crystals, proving the Y-states to
be responsible for electrical conductivity in
SrMnSb_22.
DFT and tight binding (TB) methods are used to model the electronic
states, and both show good agreement with the ARPES data. Despite the
great promise of the latter, both theory approaches show the Y-states to
be gapped above E_FF,
suggesting trivial topology. Subsequent analysis within both theory
approaches shows the Berry phase to be zero, indicating the
non-topological character of the transport in
SrMnSb_22,
a conclusion backed up by the analysis of the quantum oscillation data
from our crystals.