Electrical-transport characteristics of as-grown and oxygen-reduced La$_{0.7}$Ce$_{0.3}$MnO$_3$ films: calculation of hopping energies, Mn valences, and carrier localization lengths
Electrical-transport characteristics of as-grown and oxygen-reduced La$_{0.7}$Ce$_{0.3}$MnO$_3$ films: calculation of hopping energies, Mn valences, and carrier localization lengths
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DOI：
10.1016/j.jpcs.2014.12.014
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发表时间：
2014-08
期刊：
影响因子：
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通讯作者：
A. Thiessen;E. Beyreuther;R. Werner;R. Kleiner;D. Koelle;L. Eng
中科院分区：
文献类型：
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作者：
A. Thiessen;E. Beyreuther;R. Werner;R. Kleiner;D. Koelle;L. Eng
掺Ce的LaMnO_3被广泛认为是最有前景的电子掺杂薄膜原型材料之一，是对已有的空穴掺杂混价锰氧化物的补充。在这里，我们研究了La0.7Ce0.3MnO_3薄膜的电学性质，并验证了它们是否提供了远低于+3的有效电子掺杂。通过在90到300℃的宽温度范围内进行电阻测量，对厚度在10到100 nm之间的薄膜进行了表征，通过比较不同输运模型的实验数据，得出了它们的跳跃能、载流子局域化长度和锰价。虽然300℃以上的电子输运很好地取决于小极化子的热激活扩散，但我们发现载流子的无序局域化揭示了较低温度下的变程跳跃型输运。从研究中考察的几个参数来看，主要是氧含量和CeO2相的偏析程度是控制这类电子掺杂薄膜锰氧化物的关键。
Cerium-doped LaMnO3is widely discussed as one of the most prospective electron-doped thin-film prototype material that complements well-established hole-doped mixed-valence manganites. Here, we investigate La0.7Ce0.3MnO3films with respect to their electrical properties and check whether they provide an effective electron doping with Mn-valences well below +3. Thin films of a variable thickness between 10 and 100 nm are characterized through resistance measurements over a broad temperature range between 90 and 300 K deducing their hopping energies, carrier localization lengths, and the Mn valence by comparing the experimental data to different transport models. While electronic transport above 300 K is well determined by the thermally activated diffusion of small polarons, we find the carrier localization by disorder to reveal a variable-range hopping-type transport for lower temperatures. From the several parameters investigated in the study, it is mainly the oxygen content and the degree of CeO2phase segregation that are crucial to be controlled in such electron-doped thin-film manganites.