  SrRu2O6 is a layered honeycomb lattice material with an extraordinarily high
magnetic ordering temperature. We investigated this material using density
functional calculations. We find that the energy scales for moment formation
and ordering are similar and high. Additionally, we find that the magnetic
anisotropy is high and favors moments oriented along the $c$-axis. This
provides an explanation for the exceptionally high ordering temperature.
Finally, the compound is found to be semiconducting at the bare density
functional level, even without magnetic order. Experimental consequences of
this scenario for the high ordering temperature are discussed.
