Magnetism and ferroelectricity
Magnetic, electrical, magnetoelectrical, and magnetoelastic properties of La$_{0.9}$Sr$_{0.1}$MnO$_{3-y}$ manganites
L. I. Korolevaa,
D. M. Zashchirinskiia,
T. M. Khapaevaa,
A. L. Gurskiĭb,
N. A. Kalandac,
V. M. Trukhanb,
R. Shimchakd,
B. Krzumanskad a Lomonosov Moscow State University
b Belarussian State University of Computer Science and Radioelectronic Engineering
c Institute of Solid State Physics and Semiconductors NASB, Minsk
d Institute of Physics, Polish Academy of Sciences, Warsaw, 02-668, Poland
Abstract:
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
$_{0.9}$Sr
$_{0.1}$MnO
$_{3-y}$ 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
$\le T\le$ 300 K, the
$M(T)$ curve shows a falloff. Within the interval 240 K
$\le T\le$ 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
$\Delta\rho/\rho$ and volume magnetostriction
$\omega$ 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
$|\Delta\rho/\rho|$ and
$|\omega|$ 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.
Received: 28.04.2009
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