Effects of interaction and disorder on polarons in colossal resistance manganite Pr0.68Ca0.32MnO3 thin films
Effects of interaction and disorder on polarons in colossal resistance manganite Pr0.68Ca0.32MnO3 thin films
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相互作用和无序对巨阻锰酸锂Pr0.68Ca0.32MnO3薄膜极化子的影响
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Y. Zhu
中科院分区：
文献类型：
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作者：
J. Hoffmann;P. Moschkau;S. Mildner;J. Norpoth;C. Jooss;L. Wu;Y. Zhu
庞磁电阻效应（CMR）是掺杂锰氧化物中强关联电子的一种有趣的性质，即在强磁场中电阻值会降低几个数量级。在这里，我们提出了一个详细的分析薄膜的低带宽锰氧化物Pr0.68Ca0.32MnO3的小极化子的磁输运性质与不同程度的掺杂诱导的八面体无序。通过高分辨透射电子显微镜研究了晶体和缺陷结构。我们应用Firsov和Lang提出的小极化子理论，研究了顺磁相的跳跃迁移率及其由于反铁磁电荷有序（CO）和铁磁金属相的形成而引起的变化。虽然它代表了一个单粒子理论，合理的估计小极化子的属性，如形成能，活化能和转移积分是可能的，如果相互作用和无序的影响被考虑在内。除了众所周知的效果的磁双交换的转移积分，我们表明，出现的带运输的小极化子在CMR过渡明智地依赖于八面体无序的程度，极化子-极化子相互作用和由此产生的长程有序导致的结构相变中的CO相。
The colossal magnetoresistance effect (CMR), the drop of the electric resistance by orders of magnitude in a strong magnetic field, is a fascinating property of strongly correlated electrons in doped manganites. Here, we present a detailed analysis of the magnetotransport properties of small polarons in thin films of the low bandwidth manganite Pr0.68Ca0.32MnO3 with different degrees of preparation-induced octahedral disorder. The crystal and defect structure is investigated by means of high-resolution transmission electron microscopy. We apply the small polaron theory developed by Firsov and Lang in order to study the hopping mobility in the paramagnetic phase and its changes due to the formation of the antiferromagnetic charge ordered (CO) and the ferromagnetic metallic phases. Although it represents a single particle theory, reasonable estimates of small polaron properties such as formation energy, activation energy and transfer integral are possible, if the effects of interactions and disorder are taken into account. Beyond the well-known effect of the magnetic double exchange on the transfer integral, we show that the emergence of band transport of small polarons in the CMR transition sensibly depends on the degree of octahedral disorder, the polaron–polaron interactions and the resulting long range order leading to a structural phase transition in the CO phase.