Rivadulla F, Otero-Leal M, Espinosa A, de Andrés A, Ramos C, Rivas J, Goodenough J B
Physical-Chemistry Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Phys Rev Lett. 2006 Jan 13;96(1):016402. doi: 10.1103/PhysRevLett.96.016402. Epub 2006 Jan 4.
From Raman spectroscopy, magnetization, and thermal expansion on the system La(2/3)(Ca(1-x)Sr(x))(1/3)MnO3, we have been able to provide a quantitative basis for the heterogeneous electronic model for manganites exhibiting colossal magnetoresistance (CMR). We construct a mean-field model that accounts quantitatively for the measured deviation of T(C)(x) from the T(C) predicted by de Gennes double-exchange in the adiabatic approximation and predicts the occurrence of a first-order transition for a strong coupling regime, in accordance with the experiments. The existence of a temperature interval T(C) < T < T*, where CMR may be found, is discussed in connection with the occurrence of an idealized Griffiths phase.
通过对La(2/3)(Ca(1-x)Sr(x))(1/3)MnO3体系进行拉曼光谱、磁化和热膨胀研究，我们得以建立一个定量基础，用于解释表现出巨磁电阻（CMR）的锰氧化物的非均匀电子模型。我们构建了一个平均场模型，该模型定量地解释了在绝热近似下，T(C)(x)与由德热纳双交换预测的T(C)之间的测量偏差，并根据实验预测了强耦合 regime下一级相变的发生。结合理想化格里菲斯相的出现，讨论了可能出现CMR的温度区间T(C) < T < T*的存在情况。
