Neutron Diffraction Study of the Magnetic Structures for the Perovskite-Type Mixed Oxides La (Mn, Cr)O3
A neutron diffraction study has been made of the magnetic properties of the series of perovskite-like compounds La[(1-x)Mn, xCr]O3. This series exhibits ferromagnetic and antiferromagnetic properties which depend on the composition of the sample. The antiferromagnetic structure of pure LaMnO3 persists only for very small concentrations of Cr+3; the antiferromagnetic structure characteristic of pure LaCrO3 is found over a large composition range. For samples of intermediate composition a ferromagnetic moment is observed, the maximum occurring at about 20% Cr+3. In contrast to the mixed oxides [(1-x)La, xCa]MnO3 which for certain compositions were truly ferromagnetic, the maximum ferromagnetic moment in this series is very much less than that expected if all the spins were contributing to the moments. A complex ferrimagnetic structure is suggested for the intermediate composition range.