Changes of the local distortions and colossal magnetoresistive properties of La(0.7)Ca(0.3)MnO(3) induced by Ti or Ga defects
- LBNL Library
The magnetoresistive properties of La0.7Ca0.3MnO3 change rapidly when Ti or Ga are substituted on the Mn site for concentrations, x, from 1 to 10 percent. The samples exhibit colossal magnetoresistance (CMR) and the resistivity increases dramatically with dopant concentration. The temperature of the resistivity peak, TR, shifts rapidly to lower temperatures with increasing x and the ferromagnetic transition broadens. However, the transition temperature, Tc, is only slightly suppressed. Consequently, TR occurs well below Tc for x above 2 percent. Investigations of these materials using Mn XAFS show that changes in the local structure, parametrized by the pair-distribution width, sigma, correlate well with Tc and the sample magnetization. For a given dopant, the resistivity peak occurs when sigma{sup 2} decreases below a critical value. Both dopants produce extended defects which increases the resistivity of the nearby materials considerably. The data suggest that even at x {approx}4 percent, most of the sites are slightly distorted at low T.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director, Office of Science. Office of Basic Energy Studies. Chemical Sciences, Geosciences, and Biosciences Division (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 799649
- Report Number(s):
- LBNL--50907; B& R KC0302030
- Country of Publication:
- United States
- Language:
- English
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