Transport properties of the La1−xCaxMnO3 (0.5 ≤ x < 1)
The transport properties of the La1−xCaxMnO3 (0.5 ≤ x < 1) system in magnetic ﬁelds up to 14 T were studied. We found that the relationship between the charge ordering temperature TCO and Mn4+ content nMn4+ obeys the formula TCO/Tmax = 1−a(nMn4+ −n0)2, here n0 and a are constants and Tmax is the maximum of TCO. For x = 0.65, TCO arrives at the maximum value of 249.5 K in zero magnetic ﬁeld, while the charge ordered (CO) state is most stable around x = 0.75. For x = 0.5 when H < 6 T the resistivity displays Mott’s variable-range hopping (VRH) behavior, when 6 < H < 12 T it is suggested that two kinds of conduction mechanism, i.e., VRH and magnetic polarons, coexist in the material, and when H > 12 T the resistivity shows metallic-like behavior and the transport mechanism is attributed to coexistence of magnetic polarons and free carriers. For x = 0.95, the conduction mechanism accords with the coexistence of VRH and magnetic polarons.
Zhou, H.-D., Zheng, R.-K., Li, G., Feng, S.-J., Liu, Fan, X.-J., & Lia, X.-G. (2002). Transport properties of the La1−xCaxMnO3 (0.5 ≤ x < 1). Eur. Phys. J. B 26, 467-471.