A. Maignan et al., Ferromagnetism and metallicity in the CaMn1-xRuxO3 perovskites: a highly inhomogeneous system, SOL ST COMM, 117(6), 2001, pp. 377-382
The study of the magnetic and transport properties of the perovskites CaMn1
-xRuxO3 shows that ferromagnetism and metallicity are developed for a large
compositional range, with a much higher T-C than for SrRuO3, reaching a ma
ximum value of 210 K for x = 0.40. The greatly inhomogeneous character of t
his system, showing phase separation between ferromagnetic (FM) and antifer
romagnetic (AFM) domains, is inferred from ac-susceptibility measurements,
explaining the magneto-transport properties of these oxides. This unique ab
ility of ruthenium to induce FM and metallicity in the AFM CaMnO3 matrix is
explained by the combination of valency effect (Ru5+ species creating Mn3 species), which allows double exchange, and of FM interactions between Ru
and Mn species through super-exchange, the hybridization between Ru and Mn
e(g) orbitals favoring conduction paths in the matrix. (C) 2001 Elsevier Sc
ience Ltd. All rights reserved.