Structural changes, clustering, and photoinduced phase segregation in Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}

Journal Article · Sun Feb 01 00:00:00 EST 1998 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.57.3305· OSTI ID:568329

Cox, D E ^[1]; Radaelli, P G ^[2]; Marezio, M ^[3]; Cheong, S ^[4]

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1. Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)
2. Institut Max Von Laue-Paul Langevin, Boite Postale 156, 38042 Grenoble Cedex 09 (France)
3. MASPEC-CNR, via Chiavari 18A, 43100 Parma (Italy)
4. Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974 (United States)

The structural properties of Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3} were studied by x-ray synchrotron and neutron-powder diffraction as a function of temperature (15{lt}T{lt}300 K), and as a function of x-ray fluence at 15 and 20 K. The temperature evolution of the lattice parameters and of the superlattice reflections is consistent with the development of charge and orbital ordering below T{sub CO}{approximately}180 K, followed by antiferromagnetic ordering below T{sub N} {approximately}140 K, similar to what was previously observed for La{sub 0.5}Ca{sub 0.5}MnO{sub 3}. Below T{sub C}{approximately}120 K, the magnetic structure develops a ferromagnetic component along the a axis on the Mn ions. At low temperatures, a small ferromagnetic moment of 0.45(2){mu}{sub B} oriented in the same direction appears on the Pr ions as well. The observation in Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3} of significant lattice strain developing below T{sub CO}, as well as the development of a ferromagnetic component to the magnetic structure at T{sub C}{approximately}120 K, can be interpreted in terms of the presence of ferromagnetic clusters with an associated lattice distortion from the average structure. At low temperatures, exposure to the x-ray beam produces a phase-segregation phenomenon, whereby the ferromagnetic droplets coalesce into larger aggregates. Further exposure results in a gradual melting of the charge-ordered phase and the formation of a second phase, recently shown to be a ferromagnetic metallic phase by Kiryukhin {ital et al.} [Nature (London) {bold 386}, 813 (1997)]. The ferromagnetic phase has a significantly smaller a lattice parameter and unit-cell volume ({Delta}V/V{approximately}0.4{percent}) than that of the charge-ordered phase. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 568329
• Journal Information: Physical Review, B: Condensed Matter, Vol. 57, Issue 6; Other Information: PBD: Feb 1998
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
PRASEODYMIUM OXIDES
CALCIUM OXIDES
MANGANESE OXIDES
NEUTRON DIFFRACTION
LATTICE PARAMETERS
FERROMAGNETISM
ANTIFERROMAGNETISM
PEROVSKITES
MAGNETIC PROPERTIES
CHARGED-PARTICLE TRANSPORT
CRYSTAL STRUCTURE
MAGNETORESISTANCE
X-RAY DIFFRACTION
SEGREGATION
PHASE TRANSFORMATIONS
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION TEMPERATURE