Controlled Phase Separation in La_0.5 Ca_0.5 Mn O_3
Controlled Phase Separation in La_0.5 Ca_0.5 Mn O_3
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DOI：
10.1103/physrevb.62.6437
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发表时间：
2000-05
期刊：
影响因子：
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通讯作者：
Pablo Levy;F. Parisi;G. Polla;D. Vega;G. Leyva;H. Lanza;Rafael S. Freitas;L. Ghivelder
中科院分区：
文献类型：
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作者：
Pablo Levy;F. Parisi;G. Polla;D. Vega;G. Leyva;H. Lanza;Rafael S. Freitas;L. Ghivelder
本文系统地研究了不同热处理条件下La_（0.5）Ca_（0.5）Mn O_3多晶的分相效应。研究了平均晶粒尺寸为200 ~ 1300 nm的样品。磁性和电学测量显示了样品在低温行为方面的定量差异。表明铁磁（FM）相的分数随着晶粒尺寸的增加而逐渐减小。渗透的FM相在样品中有一小部分的这一阶段表明，晶界在共存相的空间分布中发挥着独特的作用。晶粒表面的缺陷结构可以解释反铁磁电荷有序相的局部抑制，这种效应随着晶粒尺寸的增加而逐渐消除。定性的数据与此描述的协议被发现。这种效果也被发现是高度依赖于样品的氧含量和它的空间分布。
A systematic study of phase separation effects in polycrystalline La_0.5 Ca_0.5 Mn O_3 obtained under different thermal treatments is reported. Samples with average grain size ranging from 200 to 1300 nm were studied. Magnetic and electrical measurements show quantitative differences among samples in their low temperature behavior. indicating that the fraction of the ferromagnetic (FM) phase gradually decreases as the grain size increase. Percolation of the FM phase in samples with a small fraction of this phase suggests that grain boundaries play a distinctive role in the spatial distribution of coexisting phases. The defective structure at the grain surface could explain the local inhibition of the antiferromagnetic charge ordered phase, an effect that is gradually removed with increasing grain size. Qualitative agreement of the data with this description is found. This effect is also found to be highly dependent on the oxygen content of the samples and its spatial distribution.