Structural, transport, and magnetic properties of RMnO3 perovskites (R=La, Pr, Nd, Sm, 153Eu, Dy)

The magnetic transition temperatures as a function of 〈cos2θ〉 for RMnO3 perovskites by taking TM=TN for the A-type RMnO3 (R=La-Gd) antiferromagnets with FM interactions within the ab-plane, TM=TN(IC)) for IC-type antiferromagnets, and TM=-TN for the E-type HoMnO3 antiferromagnet with the complex non-ferromagnetic interactions within the ab-plane (Phys. Rev. B 68 (2003) 060403). The TM∼〈cos2θ〉 relation remains very well satisfied for the RMnO3 perovskites despite no immediate explanation in terms of the simple superposition of antiferromagnetic and ferromagnetic interactions within the ab-plane. The critical B-O-B bond-angle within the ab-plane where the magnetic interactions change from the FM to non-FM; i.e., the Jab changes the sign is found at θcrit∼145°.