Structure, magnetism and transport of the perovskite manganites Ln0.5Ca0.5MnO3 (Ln=Ho, Er, Tm, Yb and Lu)
Structure, magnetism and transport of the perovskite manganites Ln0.5Ca0.5MnO3 (Ln=Ho, Er, Tm, Yb and Lu)
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DOI：
10.1016/j.jssc.2005.08.033
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发表时间：
2005-12
影响因子：
3.3
通讯作者：
K. Yoshii;H. Abe;N. Ikeda
中科院分区：
文献类型：
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作者：
K. Yoshii;H. Abe;N. Ikeda
结果表明：Mn（Mn）_0.5Ca（Mn）_0.5MnO_3（Ln=Ho，Er，Tm，Yb和Lu）具有正交晶系结构（空间群Pnma）。Mn-O-Mn角为148-150°，表明这些氧化物中存在较大的晶体畸变。电阻率测量表明绝缘性质和小的磁阻效应，这两者都是由于窄带宽的Mn-3d电子所产生的晶体畸变。直流磁化强度测量显示了三个特征温度，这可以被分配到电荷顺序，反铁磁性的Mn时刻，和可能的玻璃态。所有这些温度都降低了较重的Ln离子，这是解释与两个不同的离子半径的Ln 3+和Ca 2+，和降低的电子转移。只有含有最小镧系离子的Lu0.5Ca0.5MnO3的电荷有序转变没有被清楚地观察到，这可能是由于Lu 3+和Ca 2+的离子半径差异引起的磁相互作用的大的随机性。此外，交流介电响应的初步测量表明，这些锰氧化物属于所谓的多铁性系统。
It was found that the manganese perovskite oxides Ln0.5Ca0.5MnO3(Ln=Ho, Er, Tm, Yb and Lu) have an orthorhombic structure (space group Pnma). The Mn–O–Mn angles were calculated to be ∼148–150°, revealing an existence of a large crystallographic distortion in these oxides. Electrical resistivity measurements indicated both an insulating nature and a small magnetoresistance effect, both of which are owing to narrow bandwidths of the Mn-3d electrons arising from the crystallographic distortion. DC magnetization measurements showed the three characteristic temperatures, which could be assigned to charge-order, antiferromagnetism of Mn moments, and possible glassy states. All of these temperatures were decreased for the heavier Ln ions, which is explained in connection with both a difference of ionic radii of Ln3+and Ca2+, and a lowering of electron transfer. The charge-ordering transition was not clearly observed only for Lu0.5Ca0.5MnO3containing the smallest lanthanide ion, plausibly due to a large randomness of magnetic interactions arising from the ionic radii difference of Lu3+and Ca2+. In addition, preliminary measurements of AC dielectric response suggested that these manganites belong to a so-called multiferroic system.