Anomalous high pressure dependence of the Jahn-Teller phonon in La0.75Ca0.25MnO3
Anomalous high pressure dependence of the Jahn-Teller phonon in La0.75Ca0.25MnO3
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DOI：
10.1103/physrevlett.86.1251
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发表时间：
2001-02-12
影响因子：
8.6
通讯作者：
Sarma, DD
中科院分区：
文献类型：
--
作者：
Congeduti, A;Postorino, P;Sarma, DD
用金刚石对顶砧装置首次在宽气压范围（0-14 GPa）内获得了La_（0.75）Ca_（0.25）MnO_3的拉曼光谱。探索的频率范围（200-1100 cm（-1））和非常好的数据质量使我们能够仔细分析MnO 6八面体的声子模式的压力演化。结果表明，在7.5GPa附近出现了一个突变，该突变明显偏离了Jahn-Teller声子频率随压力变化的线性趋势，并伴随着强烈的声子展宽。这种行为与预测的绝缘体到金属的转变不一致，相反，表明在非常高的压力范围内发生了一个新的不可预测的阶段。
Raman spectra of La0.75Ca0.25MnO3 have been collected for the first time over a wide pressure range (0-14 GPa) using a diamond anvil cell. The frequency range explored (200-1100 cm(-1)) and the very good quality of the data allowed us to carefully analyze the pressure evolution of the phonon modes of the MnO6 octahedra. The results show an abrupt transition at similar to7.5 GPa with an evident deviation from the linear trend of the frequency of the Jahn-Teller phonon versus the applied pressure, accompanied by a strong phonon broadening. This behavior disagrees with the predicted insulator to metal transition and, on the contrary, indicates the occurrence of a new unpredicted phase in the very high pressure regime.