Lattice distortion-induced phase transformations in La{sub 1-y}Pr{sub y}MnO{sub 3+{delta}} manganites
- National Academy of Sciences of Ukraine, Donetsk Physicotechnical Institute (Ukraine)
The structural and magnetic phase transformations that occur in the system of self-doped La{sub 1-y}Pr{sub y}MnO{sub 3+{delta}} ({delta} Almost-Equal-To 0.1, 0 {<=} y {<=} 1) manganites in the temperature range 4.2-300 K are studied by X-ray diffraction and measuring the temperature and field dependences of dc magnetization. The low-temperature magnetic phase transformations induced by the substitution of Pr for La correlate well with the structural phase transformations at T = 300 K, which indicates a strong coupling of the electronic and magnetic subsystems of La{sub 1-y}Pr{sub y}MnO{sub 3+{delta}} manganites with the crystal lattice. The anomalies of the magnetic and structural properties detected in this work in the form of peaks and inflection points in the concentration dependences of the magnetization and lattice parameters of the pseudocubic phase of La{sub 1-y}Pr{sub y}MnO{sub 3+{delta}} (0.1 {<=} y {<=} 0.7) in the temperature range 4.2-300 K are explained in terms of the existing concepts of the effect of Fermi surface nesting on the renormalization of the density of states and the hole dispersion near E{sub F} in the presence of a strong coupling of holes with low-frequency optical phonons, which results in their transformation into quasiparticles. The narrow peak in the magnetization curve M(y) of La{sub 1-y}Pr{sub y}MnO{sub 3+{delta}} that is detected near y = 0.3 at T = 4.2 K is assumed to correspond to the peak of coherence of quasiparticles with a low energy of coupling with the crystal lattice near E{sub F}, which was found earlier in the photoelectron emission spectra of manganites. The disappearance of the narrow magnetization peak with increasing Pr concentration is explained by the transition of charge carriers from the mode of 'light' holes weakly coupled to one of the soft phonons to the mode of 'heavy' holes strongly coupled to several phonons. The transition between phases with strongly different effective quasiparticle masses proceeds jumpwise; that is, it has features of the metal-insulator Mott transition and is accompanied by the transition from 3D to 2D quasiparticle motion in planes ab.
- OSTI ID:
- 22126557
- Journal Information:
- Journal of Experimental and Theoretical Physics, Vol. 116, Issue 4; Other Information: Copyright (c) 2013 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
Similar Records
Investigation of dielectric relaxation, Jahn-Teller distortion, and magnetic ordering in Y substituted Pr{sub 1−x}Y{sub x}MnO{sub 3} (0.1 ≤ x ≤ 0.4)
Effect of phase separation induced supercooling on magnetotransport properties of epitaxial La{sub 5/8−y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (y≈0.4) thin film
Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHARGE CARRIERS
CONCENTRATION RATIO
CRYSTAL LATTICES
DOPED MATERIALS
EMISSION SPECTRA
FERMI LEVEL
LANTHANUM COMPOUNDS
LATTICE PARAMETERS
MAGNETIZATION
MANGANATES
PHASE TRANSFORMATIONS
PHONONS
PRASEODYMIUM
PRASEODYMIUM COMPOUNDS
RENORMALIZATION
STRONG-COUPLING MODEL
TEMPERATURE RANGE 0065-0273 K
X-RAY DIFFRACTION