Letter to the Editor - Effect of Substitution of Cr31 in Place of Mn31 in Rare-Earth Manganates on the Magnetism and Magnetoresistance: Role of Superexchange Interaction and Lattice Distortion in LnMn(1-x)Cr(x)O(3)1

Abstract

Magnetic and electrical properties of oxides of the formulaLnMn1−xCrxO3(Ln= rare earth) have been investigated to understand the importance of the Mn3+–O–Cr3+superexchange interactions, in contrast to theLn1−xAxMnO3(A= divalent cation) system, where double exchange interactions predominate. All theLnMn1−xCrxO3compositions are ferromagnetic insulators and exhibit small values of negative magnetoresistance (MR) at ordinary temperatures, the highest value of MR at 6 T being ∼20% at 120 K for some of the compositions. The results underscore the important role of double exchange, as well as lattice distortion effects, in giving rise to high values of MR inLn1−xAxMnO3.