Magnetic interaction in Mg, Ti, Nb doped manganites
I. O. Troyanchuk1a, M. V. Bushinsky1, H. Szymczak2, K. Bärner3 and A. Maignan4
Institute of Solid State and Semiconductor Physics of National Academy of Sciences, P.
Brovka str. 17, 220072 Minsk, Belarus
2 Institute of Physics, Polish Academy of Sciences, al. Lotnikov 32/46, 02-668 Warsaw, Poland
3 4. Physikalishes Institut der Göttingen Universität, Bunsenstraße 13, 37073 Göttingen, Germany
4 Laboratoire CRISMAT, ISMRA, Université de Caen, 6 Boulevard du maréchal Juin, 14050 Caen Cedex, France
Corresponding author: a email@example.com
Published online: 9 July 2002
An effect of Mn substitution with Me=Mg2+, Ti4+, Nb5+ in manganites has been investigated by preparing La0.7Sr0.3(MnMex)O3 and LaSrx(MnNb)O3 series. It was established that substitution of manganese with magnesium up to x=0.16 leads to a collapse of a long-range ferromagnetic order whereas La0.7Sr0.3(MnNb)O3 is ferromagnet with TC=123 K and exhibits a large magnetoresistance below Curie point despite an absence of four-valent manganese. Hypothetical magnetic phase diagrams are constructed for La0.7Sr0.3(MnMex)O3 and LaSrx(MnNb)O3. Our results show that Mn3+-O-Mn3+ exchange interaction is ferromagnetic in the orbitally disordered manganites as well as an increase of Mn4+ content above 50% from a total amount of manganese ions leads to formation of a spin glass state due to a competition between antiferromagnetic Mn4+-O-Mn4+ and ferromagnetic Mn3+-O-Mn4+(Mn3+) superexchange interactions.
PACS: 75.30.Kz – Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) / 75.30.Vn – Colossal magnetoresistance / 75.30.Et – Exchange and superexchange interactions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002