Study of magnetic properties of A2B′NbO6 (A = Ba,Sr,BaSr; and B′ = Fe and Mn) double perovskites

We have studied the magnetic properties of Ba2FeNbO6 and Ba2MnNbO6. It is seen that Ba2FeNbO6 is an antiferromagnet with a weak ferromagnetic behavior at 5 K while Ba2MnNbO6 shows two magnetic transitions, one at 45 K and the other at 12 K. Electron spin resonance measurements at room temperature show that the Mn compound does not show any Jahn-Teller distortion. It is also seen that the Neel temperatures of the A(2)FeNbO(6) (A=Ba,Sr,BaSr) compounds do not vary significantly. However variations in the average A-site ionic radius influence the formation of short range correlations that persist above T-N. (C) 2004 American Institute of Physics.