Low Temperature Physics: 37, 843 (2011); https://doi.org/10.1063/1.3670028 (4 pages)
Fizika Nizkikh Temperatur: Volume 37, Number 9-10 (September 2011), p. 1057-1061 ( to contents , go back )
Low-temperature magnetically-inhomogeneous states in Sr2FeMoO6–δ compounds
N.A. Kalanda, S.E. Demyanov, and L.V. Kovalev
Scientific-Practical Materials Research Centre of Belarus, NAS, 19 P. Brovka Str., Minsk 220072, Belarus
Received February 28, 2011
It is shown, that the degree of inhomogeneity of the Sr2FeMoO6–δ metal oxide compound microstructure, that essentially depends on synthesis conditions, leads to different degrees of superstructural ordering of Fe3+ and Mo5+ cations. According to the temperature dependences of magnetization of the samples measured without any magnetic field, the sharp jump in the low temperature region (2.3–23 K) indicates that there are magnetic regions with low coercitive force, where the superparamagnetic state is realized. It is established that magnetic inhomogeneity of antiferromagnetic– ferrimagnetic states promotes a frustration of the exchange coupling and facilitates a realization of the spin glass state in the material. A decrease of magnetic inhomogeneity and corresponding increase of the degree of superstructural ordering of cations cause the negative magnetoresistance effect to increase up to 14%, and to be unchanged at temperature below 15 K.
PACS: 75.10.–b General theory and models of magnetic ordering;
Key words: double perovskite, magnetoresistance, magnetization.