  We have investigated the structural and magnetic properties of
antiferroelectric $A_2$CoTeO$_6$ perovskites with $A$ = Cd, Ca, Sr, Pb, and Ba.
All compounds are antiferromagnetic at low temperatures, with the
antiferromagnetic transition temperature slightly decreasing with decreasing
ionic size of the $A$ cation. Such a decrease in antiferromagnetic interaction
is not observed in $A^{2+}_2$Co$M^{6+}$O$_6$ materials with other $M^{6+}$
cations of similar ionic sizes, suggesting that Te$^{6+}$ cations affect the
electronic and in turn the magnetic structure of the system.
