Magnetic, electrical, and optical properties of electron-doped Ca{sub 1-x}La{sub x}MnO{sub 3-{delta}}(x {<=} 0.12) single crystals
- Russian Academy of Science, Institute of Metal Physics, Ural Division (Russian Federation)
- Moscow Power Engineering Institute (Russian Federation)
The magnetic, electrical, and optical properties of Ca{sub 1-x}La{sub x}MnO{sub 3-{delta}}(x {<=} 0.12) manganite single crystals have been studied. The state with a spatially inhomogeneous electron distribution has been found. Interrelations between the electric and magnetic subsystems are analyzed. The obtained magnetic data show evidence for the formation of a G-type antiferromagnetic (G-AFM) phase with a spin-canted structure in the crystal with x = 0.05, for which the Curie and Neel temperatures are T{sub C} T{sub N}(G) = 115 K. On cooling from the paramagnetic state, the crystals with x 0.10 and 0.12 exhibit transitions from the paramagnetic to a C-type antiferromagnetic (C-AFM) phase in a part of the volume at T{sub N}(C) = 150 and 200 K, and from the paramagnetic to the G-type antiferromagnetic (G-AFM) phase in the remaining volume at T{sub N}(G) = 110 and 108 K, respectively. The onset of the C-type magnetic phase nucleation in crystals is observed at lower dopant (La) concentrations than in polycrystalline samples, which is explained by the deviation of single crystals from the stoichiometry with respect to oxygen. The magnetic phase transitions are manifested by anomalies in the electric resistance and magnetoresistance of doped crystals. An analysis of the electrical and optical properties of the samples shows evidence of (i) the formation of a charge energy gap in the C-AFM phase with retained paramagnetic metallic regions and (ii) the presence of ferromagnetic 'metallic' droplets in the insulating G-AFM phase. The multiphase state of Ca{sub 1-x}La{sub x}MnO{sub 3-{delta}} manganite single crystals featuring the coexistence of two magnetic phases, the regions with orbital/charge ordering, and the FM 'metallic' droplets is related to a competition of exchange interactions by the superexchange and double exchange mechanisms.
- OSTI ID:
- 21067742
- Journal Information:
- Journal of Experimental and Theoretical Physics, Vol. 102, Issue 2; Other Information: DOI: 10.1134/S1063776106020051; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTIFERROMAGNETISM
ATOMIC FORCE MICROSCOPY
CALCIUM COMPOUNDS
DOPED MATERIALS
ELECTRONS
EXCHANGE INTERACTIONS
LANTHANUM COMPOUNDS
MAGNETORESISTANCE
MANGANATES
MONOCRYSTALS
NEEL TEMPERATURE
NUCLEATION
OPTICAL PROPERTIES
PARAMAGNETISM
PHASE TRANSFORMATIONS
POLYCRYSTALS
SPIN
STOICHIOMETRY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K