https://doi.org/10.1140/epjb/e2004-00357-8
Influence of oxygen vacancies on the magnetic and electrical properties of La1-xSrxMnO3-x/2 manganites
1
Institute of Solids and Semiconductor Physics, National Academy of Sciences of Belarus, P. Brovka str. 17, 220072 Minsk, Belarus
2
Laboratoire CRISMAT, ISMRA, 6 Boulevard du Maréchal Juin 14050 Caen Cedex, France
3
Institute of Physics, Polish Academy of Sciences, Lotnikov str. 32/46, 02-668 Warsaw, Poland
Corresponding author: a truhanov@ifttp.bas-net.by
Received:
30
April
2004
Revised:
14
July
2004
Published online:
26
November
2004
The crystal structure, magnetization and electrical transport depending on
the temperature and magnetic field for the doped stoichiometric
as well as anion-deficient
(
) ortomanganite systems have been experimentally studied. It
is established that the stochiometric samples in the region of the
are an
-orthorhombic perovskites whereas in the
– a rhombohedric. For the anion-deficient system the symmetry type of the unit cell is similar to the stoichiometric one. As
a doping level increases the samples in the ground state undergo a number of
the magnetic transitions. It is assumed that the samples with the large
amount of oxygen vacancies are a cluster spin glasses (
) and temperature of the magnetic moment freezing is ~40 K. All the anion-deficient samples are semiconductors and show considerable magnetoresistance over a wide temperature range with a peak for the
x = 0.175 only. Concentration dependences of the spontaneous magnetization
and magnetic ordering temperature for the anion-deficient
system have been established by the
magnetic measurements and compared with those for the stoichiometric
one. The
magnetic propeprties of the anion-deficient samples may be interpreted on
the base of the superexchange interaction and phase separation (chemical
disorder) models.
PACS: 75.30.Kz – Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.) / 75.30.Vn – Colossal magnetoresistance / 75.50.Dd – Nonmetallic ferromagnetic materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004