Exchange coupling and electronic structure of La{sub 1{minus}x}Ca{sub x}MnO{sub 3}: Effect of lattice distortion, canting, and doping (abstract)

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364785· OSTI ID:662023

Mryasov, O N ^[1]; Sabiryanov, R F ^[2]; Freeman, A J ^[1]; Jaswal, S S ^[2]

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1. Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208 (United States)
2. Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska (United States)

The influence of lattice distortion, canting of magnetic moments, and doping on the exchange coupling and the electronic structure of La{sub 1{minus}x}Ca{sub x}MnO{sub 3} was studied using a generalization of the linear muffin-tin orbital (LMTO) method for noncollinear magnetic ordering and the LMTO{endash}Green function technique in single-site approximation. Jahn{endash}Teller type lattice distortions (f), including rotation and tilting of the oxygen octahedra, were varied from the ideal orthorhombic phase (f=0) to the observed structure (f=1). The canting angle ({Theta}) is considered also as a simulation parameter which is varied from {Theta}=0{degree} ferromagnetic (FM) phase to {Theta}=180{degree} antiferromagnetic (AFM). The effect of doping was simulated for x=1.,0.5,0 ordered alloys. We found that (i) doping and change of the magnetic ordering (from FM to AFM) promotes the competition between positive e{sub g} and negative t{sub 2g} contributions to the exchange coupling between ferromagnetic sheets (J{sup {perpendicular}}); (ii) the J{sup {perpendicular}} exchange is strongly of non-Heisenberg type, the bilinear contribution changes sign from positive to negative at f{approximately}0.75; (iii) the metal{endash}semiconductor transitions occur for {Theta}{ge}120{degree} and for distortions f{ge}0.6. {copyright} {ital 1997 American Institute of Physics.}

• DOE Contract Number: FG02-88ER45372
• OSTI ID: 662023
• Report Number(s): CONF-961141--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CRYSTAL STRUCTURE
DOPED MATERIALS
ELECTRONIC STRUCTURE
EXCHANGE INTERACTIONS
FERROMAGNETIC MATERIALS
JAHN-TELLER EFFECT
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
LATTICE PARAMETERS
MAGNETIC MOMENTS
MANGANESE OXIDES
MOLECULAR ORBITAL METHOD
MUFFIN-TIN POTENTIAL