Structural and magnetic properties of La{sub 1-x}Pr{sub x}MnO{sub 3+{delta}} (0{<=}x{<=}1.0)
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland)
- A. A. Galkin Donetsk Physico-Technical Institute NASU, 83114 Donetsk (Ukraine)
- M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)
- Institute of Physics, Technical University of Krakow, PodchoraPzych 1, 30-084 Cracow (Poland)
- BENSC, Hahn-Meitner Institute, Glienicker Strasse 100, D-14109 Berlin-Wannsee (Germany)
X-ray, neutron powder diffraction (NPD), and magnetic measurements were performed in order to investigate the effect of Pr substitution for La on crystallographic structure, on character of magnetic ordering, and on transition temperature in La{sub 1-x}Pr{sub x}MnO{sub 3+{delta}} manganites series (0{<=}x{<=}1.0). Strong dependence of structural and magnetic properties on average A-site ionic radius was found. The magnetic phase diagram, characterizing Pr concentration dependence of the phase transition temperature, was constructed, based on magnetic and on NPD results. In the compounds with x<0.7, the ferromagneticlike behavior with ferromagnetic moment aligned along the b axis was observed in the temperature interval below the Curie temperature, T{sub C}, varying in the range of 113-153 K, down to Mn ions canted spin arrangement transition temperature, T{sub CANT}, varying in the range of 73-115 K. It was found that T{sub C} changes nonmonotonously with Pr content, it decreases rapidly for x<0.3 and for x>0.6, while is practically independent on x for 0.3<x<0.6. The Mn magnetic moments increase from 3.2 for x=0 to 3.6 for x=0.3 before decreasing to 1.7 {mu}{sub B}/Mn for x=1.0 and form a canting structure with canting angle decreasing from 32 deg. for x=0 to 16 deg. for x=0.3 and then increasing to 70 deg. for x=1.0. The NPD and x-ray diffraction data indicate that Pr doping in LaMnO{sub 3} is accompanied by changes of both the lattice parameters and crystal structure. The compound with x=0 was shown to have a rhombohedral crystal structure, while the samples with 0.1{<=}x{<=}0.6 have orthorhombic symmetry with a small Jahn-Teller distortion (or pseudocubic) which continuously transforms towards highly distorted orthorhombic structure for x>0.6. From ac magnetic susceptibility, studied under hydrostatic pressure up to 1.5 GPa, it was found that T{sub C} and T{sub CANT} change linearly with an applied pressure. The results are interpreted taking into account the competition of ferromagnetic double-exchange and antiferromagnetic superexchange interactions. This competition leads to a low temperature disordered system with spin canted features as a result of a decrease of the average A-site cation radius followed by decrease of Mn-O bond lengths, Mn-O-Mn bond angles, and the static Jahn-Teller distortion of the MnO{sub 6} octahedra.
- OSTI ID:
- 20853330
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 74, Issue 2; Other Information: DOI: 10.1103/PhysRevB.74.024418; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETIC MATERIALS
ANTIFERROMAGNETISM
BOND ANGLE
BOND LENGTHS
CATIONS
CONCENTRATION RATIO
CURIE POINT
FERROMAGNETIC MATERIALS
JAHN-TELLER EFFECT
LANTHANUM COMPOUNDS
LATTICE PARAMETERS
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
MANGANATES
MANGANESE IONS
NEUTRON DIFFRACTION
ORTHORHOMBIC LATTICES
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PRASEODYMIUM COMPOUNDS
PRESSURE RANGE GIGA PA
SPIN
X-RAY DIFFRACTION