ISSN:
1434-6036
Keywords:
PACS. 75.30.Kz Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) – 75.30.Vn Colossal magnetoresistance – 75.30.Et Exchange and superexchange interactions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract: An effect of Mn substitution with Me=Mg2+, Ti4+, Nb5+ in manganites has been investigated by preparing La0.7Sr0.3(Mn1-xMex)O3 and La1-xSrx(Mn1 - x/2Nbx/2)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(Mn 3 + 0.85Nb 5 + 0.15)O3 is ferromagnet with T C = 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(Mn1-xMex)O3 and La1-xSrx(Mn1 - x/2Nbx/2)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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1140/epjb/e2002-00202-2
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