Physical properties of the giant magnetoresistive perovskite system La-Er-Ca-Mn-O

The effect of minor changes in lattice parameters and Mn3+/Mn4+ ratios on the magnetoresistive and related properties of the La-Er-Ca-Mn-O perovskite system have been investigated. The latter is found to be the more important factor in determining the magnetotransport properties of these materials. One composition has been prepared by both the standard ceramic method as well as a sol-gel technique. Although the general features of the magnetotransport properties of these two samples were very similar, the magnetic properties showed significant differences. Experimental results are explained on the basis of a spin-dependent mechanism which is related to lattice distortion. (author)