Effect of compositional fluctuations on the phase transitions in (Nd1/2Sr1/2)MnO3
Effect of compositional fluctuations on the phase transitions in (Nd1/2Sr1/2)MnO3
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DOI：
10.1021/cm990281d
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发表时间：
1999-12-01
影响因子：
8.6
通讯作者：
Cheetham, AK
中科院分区：
文献类型：
--
作者：
Woodward, PM;Cox, DE;Cheetham, AK
采用高分辨率同步加速器X射线和中子粉末衍射技术研究了两种名义成分为（Nd0.5Sr0.5）MnO 3的多晶样品的结构和磁性相变。第一个样品在低温下分离成三个共存的宏观相：铁磁（FM）相，轨道有序的反铁磁A型（AFM-A）相，和多数相，其显示电荷，轨道和反铁磁CE型（AFM-CE）排序。第二个示例显示了从FM状态到AFM-CE状态的清晰过渡。第一个样品的不寻常的行为与Mn 4+的略微过量和相对于第二个样品的更宽的组成范围相关，并且说明了在Mn 4+：Mn 3+的统一比率附近这三种状态之间的非常微妙的竞争，其中已知发生电子离域和电荷有序。报道了Nd_（0.5）Sr_（0.5）MnO_3的电荷有序结构。
High-resolution synchrotron X-ray and neutron powder diffraction techniques have been used to investigate the structural and magnetic phase transitions in two polycrystalline samples with nominal composition (Nd0.5Sr0.5)MnO3. The first sample separates into three coexisting macroscopic phases at low temperature: a ferromagnetic (FM) phase, an orbitally ordered antiferromagnetic A-type (AFM-A) phase, and the majority phase, which shows charge, orbital, and antiferromagnetic CE-type (AFM-CE) ordering. The second sample shows a clean transition from the FM state into the AFM-CE state. The unusual behavior of the first sample is associated with a slight excess of Mn4+ and a wider compositional range with respect to the second sample and illustrates the very delicate competition between these three states near a Mn4+:Mn3+ ratio of unity, where both electron delocalization and charge-ordering are known to occur. The charge-ordered structure of Nd0.5Sr0.5MnO3 is reported.