Magnetic, electrical, magnetoelectrical, and magnetoelastic properties of [La.sub.0.9][Sr.sub.0.1]Mn[O.sub.3-y] manganites

• Published in: Physics of the solid state 2010-01, Vol.52 (1), p.96
• Main Authors: Koroleva, L.I, Zashchirinskii, D.M, Khapaeva, T.M, Gurskii, L.I, Kalanda, N.A, Trukhan, V.M, Szymczak, R, Krzumanska, B
• Format: Article
• Language: English
• Subjects: Analysis; Ferromagnetism; Magnetic properties; Magnetization; Toy industry
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783410010166

This paper reports on a study of the influence of oxygen deficiency on the magnetization, paramagnetic susceptibility, electrical resistivity, magnetoresistance, and volume magnetostriction of the [La.sub.0.9][Sr.sub.0.1]Mn[O.sub.3-y] manganite with y = 0.03, 0.10, and 0.15. The magnetization M(T) behaves in a complex way with temperature; for T< 80 K, it only weakly depends on T, and at 80 ≤ T ≤ 300 K, the M(T) curve shows a falloff. Within the interval 240 K ≤ T ≤ 300 K, the long-range magnetic order breaks up into superparamagnetic clusters. For T < 80 K, the magnetic moment per formula unit is about one-fourth that which should be expected for complete ferromagnetic alignment of Mn ion moments. Although the composition with y = 0.03, in which part of acceptor centers is compensated by donors (oxygen vacancies), the negative magnetoresistance Ap/p and volume magnetostriction co are observed to pass through maxima near the Curie point, their values are one to two orders of magnitude smaller than those for the y = 0 composition. In compositions with y = 0.10 and 0.15 with electronic doping, the values of Ap/p and co are smaller by one to two orders of magnitude than those observed for the y = 0.03 composition. They do not display giant magnetoresistance and volume magnetostriction effects, which evidences the absence of ferrons near unionized oxygen vacancies. This allows the conclusion that the part played by both compensated and uncompensated doubly charged donors consists in forming dangling Mn-O-Mn bonds, which lead to a decrease in the Curie temperature with increasing y and to the formation above it of superparamagnetic clusters of the nonferron type.