ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
La2/3Ca1/3MnO3 is a strong double-exchange ferromagnet where the ratio of La3+–Ca2+ 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 La2/3Ca1/3(Mn1−xCox)O3 and La2/3Ca1/3(Mn1−xNix)O3 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 La2/3Ca1/3MnO3 (with up to 50% Co or Ni substitution) by a series of anneals at 1300 °C followed by repeated grindings. We have investigated the magnetization, electrical conductivity, and thermopower of these mixed transition-metal perovskites. For La2/3Ca1/3(Mn1−xCox)O3, the magnetization decreases with added Co, but ferromagnetism is retained (at least up to 50% Co). Although metallic conductivity is still present at 10% Co concentration, these Co–Mn perovskites become insulating for x≥0.2. For La2/3Ca1/3(Mn1−xNix)O3, the metallic state is retained at least until x=0.5. The magnetic properties exhibit spin-glasslike behavior for x≥0.25. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.364929
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