  The technique of spin-polarized scanning tunneling microscopy is investigated
for its use in determining fine details of surface magnetic structure down to
the atomic scale. As a model sample, the row-wise anti-ferromagnetic Mn3N2(010)
surface is studied. It is shown that the magnetic contrast in atomic-scale
images is a strong function of the bias voltage around the Fermi level.
Inversion of the magnetic contrast is also demonstrated. The experimental
SP-STM images and height profiles are compared with simulated SP-STM images and
height profiles based on spin-polarized density functional theory. The success
of different tip models in reproducing the non-magnetic and magnetic STM data
is explored.
