  The magnetic structure of the double perovskite compound Sr$_2$CuTeO$_6$ was
determined from neutron powder diffraction data. This material is magnetically
described as an $S\,{=}\,1/2$ quasi-two-dimensional square-lattice Heisenberg
model with antiferromagnetic nearest-neighbor and next-nearest-neighbor
interactions. Sr$_2$CuTeO$_6$ undergoes a magnetic phase transition at $T_{\rm
N}\,{\simeq}\,29\,$ K. The spin structure below $T_{\rm N}$ is N\'{e}el
antiferromagnetic on the square lattice, which means that the nearest-neighbor
interaction ($J_1$) is stronger than the next-nearest-neighbor interaction
($J_2$), in contrast to other isostructural compounds such as Ba$_2$CuWO$_6$
and Sr$_2$CuWO$_6$, for which $|J_1|\,{<}\,|J_2|$ is realized.
