https://doi.org/10.1007/s10051-001-8693-2
Ferromagnetism in lacunar perovskite manganites Pr0.7Sr0.3-x xMnO3 and Pr0.7-x xSr0.3MnO3
1
Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, BP 802, 3018 Sfax, Tunisia
2
Laboratoire des Matériaux et du Génie Physique (ENSPG-CNRS (UMR-5628)) , BP 46,
38402 Saint Martin d'Hères Cedex, France
Corresponding author: a Abdel.Cheikhrouhou@fss.rnu.tn
Received:
12
April
2000
Revised:
8
January
2001
Published online: 15 December 2001
Deficiency effects in the A site upon the structural, magnetic and electrical properties in the lacunar perovskite manganite oxides Pr0.7Sr
xMnO3 (
) and Pr
xSr0.3MnO3 (
) have been investigated. This study focuses on the
different parameters which govern the magnetic and electrical properties in such samples.
The powder X-ray diffraction patterns for all samples could be indexed either with a rhombohedral
perovskite structure and R
c space group for
in strontium deficient samples and for
for praseodymium deficient ones. For other values of x the samples could be indexed in the orthorhombic structure with Pbnm space group. Magnetic and electrical investigations show that
praseodymium and strontium vacancies do not have similar effects on the lacunar compounds.
Magnetization measurements versus temperature show that all our samples exhibit a
magnetic transition when the temperature decreases. All the praseodymium deficient samples
exhibit a paramagnetic-ferromagnetic transition when the temperature decreases while the
strontium deficient ones exhibit this transition only for low x values. The magnetic transition
temperature shifts to lower values as the strontium deficiency increases (from 265 K for x = 0
to 90 K for x = 0.3) and to higher values with the praseodymium deficiency increase (from
265 K for x = 0 to 315 for x = 0.23).
Resistivity measurements as a function of temperature show a semiconducting-metallic
transition for all x values in the praseodymium lacunar samples and only for low x values
(
) in the strontium lacunar ones when the temperature decreases.
PACS: 71.20.Ps – Other inorganic compounds / 71.30.+h – Metal-insulator transitions and other electronic transitions / 75.50.-y – Studies of specific magnetic materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001