Abstract

Cooperative phenomena constitute important mechanisms to explain the magnetic properties of the perovskite manganites REMnO3, in which the rare-earth and/or Mn is partially replaced by divalent elements. In this way, the manganese ion changes its valence state (Mn3+ → Mn4+), triggering strong magnetic interactions. In this work we describe the case of GdCox Mn1-x O3 (0.0 ≤ × ≤ 1.0) for which the antiferromagnetic interaction between the Gd sublattice and the Mn/Co network leads to a reversal of the magnetic moment at low temperature. No inversion is observed for the LaCox Mn1-x O3 series, in which the ordering temperature may attain a maximum of 235 K for LaCo0.50 Mn0.50 O3, while it is only 120 K for similar Co/Mn ratio in the case of GdCo0.50 Mn0.50 O3. Magnetic properties are described in terms of two regimes: one, for × < 0.5, when Co substitutes Mn in the GdMnO3 manganite and another one, for x > 0.5, when Mn substitutes Co in the GdCoO3 cobaltite, while the magnetic interactions are maximized at x(Co) = 0.50. This hypothesis is discussed in terms of the respective oxidation states of both manganese (Mn3+/ Mn4+) and cobalt (Co2+/Co3+).