Influence of the $A$ cation on the low-temperature antiferromagnetism of ordered antiferroelectric $A_2$CoTeO${}_6$ perovskites

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.