La(0.55)Ca(0.45)MnO(3)中纳米级相分离的直接成像：与巨磁电阻的关系
Direct imaging of nanoscale phase separation in La(0.55)Ca(0.45)MnO(3): relationship to colossal magnetoresistance.
作者信息
Tao J, Niebieskikwiat D, Varela M, Luo W, Schofield M A, Zhu Y, Salamon M B, Zuo J M, Pantelides S T, Pennycook S J
机构信息
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
出版信息
Phys Rev Lett. 2009 Aug 28;103(9):097202. doi: 10.1103/PhysRevLett.103.097202. Epub 2009 Aug 27.
A nanoscale phase is known to coincide with colossal magnetoresistance (CMR) in manganites, but its volume fraction is believed to be too small to affect CMR. Here we provide scanning-electron-nanodiffraction images of nanoclusters as they form and evolve with temperature in La(1-x)Ca(x)MnO(3), x = 0.45. They are not doping inhomogeneities, and their structure is that of the bulk compound at x = 0.60, which at low temperatures is insulating. Their volume fraction peaks at the CMR critical temperature and is estimated to be 22% at finite magnetic fields. In view of the known dependence of the nanoscale phase on magnetic fields, such a volume fraction can make a significant contribution to the CMR peak.
已知在锰氧化物中，纳米尺度的相与巨磁电阻（CMR）现象同时出现，但其体积分数被认为太小，无法影响巨磁电阻。在此，我们提供了在La(1-x)Ca(x)MnO(3)（x = 0.45）中纳米团簇形成并随温度演化时的扫描电子纳米衍射图像。它们并非掺杂不均匀性，其结构是x = 0.60时体相化合物的结构，在低温下是绝缘的。它们的体积分数在巨磁电阻临界温度处达到峰值，在有限磁场下估计为22%。鉴于已知纳米尺度的相对磁场的依赖性，这样的体积分数能够对巨磁电阻峰值做出显著贡献。
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