(La_(1-x)Pr_x)_(0.7)Ca_(0.3)MnO_3 COLOSSAL MAGNETORESISTIVE MATERIALS: STRUCTURE AND ELECTRONIC PROPERTIES

摘要

To sum up, we have found a colossal oxygen isotope shift of the maximum resistivity temperature for (La_(1-x)Pr_x)_(0.7)Ca_(0.3)MnO_3 near critical tolerance factor value 0.91. The magnitude of the effect is a vivid demonstration of the importance of the electron-phonon coupling in R_(1-y)M_yMnO_3 waiting for a theoretical comprehension. Also, the lattice strain in thin films becomes important for electrical properties when t is close to 0.91. On the other hand, the shift of T_p during high temperature annealing is not due to the strain relaxation because it happens even without such relaxation. A plausible reason for the shift of T_p is a clustering influenced by the annealing.