Charge, orbital, and magnetic ordering in La{sub 0.5}Ca{sub 0.5}MnO{sub 3}

Journal Article · Sat Feb 01 04:00:00 EST 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.3015· OSTI ID:450367

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

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

The unusual magnetic properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3} were found to be associated with structural and magnetic ordering phenomena, resulting from the close interplay between charge, orbital, and magnetic ordering. Analysis of synchrotron x-ray and neutron powder diffraction data indicates that the anomalous and hysteretic behavior of the lattice parameters occurring between T{sub C}{approximately}225 K and T{sub N}{approximately}155 K is due to the development of a Jahn-Teller (J-T) distortion of the MnO{sub 6} octahedra, the d{sub z}{sup 2} orbitals being oriented perpendicular to the orthorhombic b axis. We observed an unusual broadening of the x-ray Bragg reflections throughout this temperature region, suggesting that this process occurs in stages. Below T{sub N}, the development of well-defined satellite peaks in the x-ray patterns, associated with a transverse modulation with q=[1/2{minus}{var_epsilon},0,0], indicates that quasicommensurate ({var_epsilon}{approximately}0) orbital ordering occurs within the a-c plane as well. The basic structural features of the charge-ordered low-temperature phase were determined from these satellite peaks. The low-temperature magnetic structure is characterized by systematic broadening of the magnetic peaks associated with the {open_quotes}Mn{sup +3}{close_quotes} magnetic sublattice. This phenomenon can be explained by the presence of magnetic domain boundaries, which break the coherence of the spin ordering on the Mn{sup +3} sites while preserving the coherence of the spin ordering on the Mn{sup +4} sublattice as well as the identity of the two sublattices. (Abstract Truncated)

• OSTI ID: 450367
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 5 Vol. 55; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BRAGG REFLECTION
CALCIUM OXIDES
CRYSTAL STRUCTURE
DOMAIN STRUCTURE
LANTHANUM OXIDES
LATTICE PARAMETERS
MAGNETISM
MANGANESE OXIDES
NEUTRON DIFFRACTION
PEROVSKITES
X-RAY DIFFRACTION