Transport and magnetism in La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3} and La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3} (abstract)
- U.S. Naval Research Laboratory, Washington, D.C. 20375 (United States)
La{sub 2/3}Ca{sub 1/3}MnO{sub 3} is a strong double-exchange ferromagnet where the ratio of La{sup 3+}{endash}Ca{sup 2+} ions has been chosen to maximize its favorable magnetic and transport properties. The Mn ion is unique as an effective participant in the double-exchange process. It is of interest to add Ni or Co atoms substitutionally for Mn in the form of La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3} and La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3} in order to determine the relative importance of the double-exchange interaction as the Mn concentration is reduced. Powder x-ray diffraction reveals we can retain the original orthorhombic structure of La{sub 2/3}Ca{sub 1/3}MnO{sub 3} (with up to 50{percent} Co or Ni substitution) by a series of anneals at 1300{degree}C followed by repeated grindings. We have investigated the magnetization, electrical conductivity, and thermopower of these mixed transition-metal perovskites. For La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Co{sub x})O{sub 3}, the magnetization decreases with added Co, but ferromagnetism is retained (at least up to 50{percent} Co). Although metallic conductivity is still present at 10{percent} Co concentration, these Co{endash}Mn perovskites become insulating for x{ge}0.2. For La{sub 2/3}Ca{sub 1/3}(Mn{sub 1{minus}x}Ni{sub x})O{sub 3}, the metallic state is retained at least until x=0.5. The magnetic properties exhibit spin-glasslike behavior for x{ge}0.25. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 496542
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 97:016235
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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