Kimura Masatoshi, He Xinyi, Katase Takayoshi, Tadano Terumasa, Tomczak Jan M, Minohara Makoto, Aso Ryotaro, Yoshida Hideto, Ide Keisuke, Ueda Shigenori, Hiramatsu Hidenori, Kumigashira Hiroshi, Hosono Hideo, Kamiya Toshio
Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan.
PRESTO, Japan Science and Technology Agency, 7 Gobancho, Chiyoda, Tokyo 102-0076, Japan.
Nano Lett. 2021 Nov 10;21(21):9240-9246. doi: 10.1021/acs.nanolett.1c03143. Epub 2021 Oct 28.
An unusually large thermopower () enhancement is induced by heterostructuring thin films of the strongly correlated electron oxide LaNiO. The phonon-drag effect, which is not observed in bulk LaNiO, enhances for thin films compressively strained by LaAlO substrates. By a reduction in the layer thickness down to three unit cells and subsequent LaAlO surface termination, a 10 times enhancement over the bulk value is observed due to large phonon drag (), and the contribution to the total occurs over a much wider temperature range up to 220 K. The enhancement originates from the coupling of lattice vibration to the d electrons with large effective mass in the compressively strained ultrathin LaNiO, and the electron-phonon interaction is largely enhanced by the phonon leakage from the LaAlO substrate and the capping layer. The transition-metal oxide heterostructures emerge as a new playground to manipulate electronic and phononic properties in the quest for high-performance thermoelectrics.
通过对强关联电子氧化物LaNiO薄膜进行异质结构处理，可诱导出异常大的热电功率（）增强效应。在块状LaNiO中未观察到的声子拖拽效应，在由LaAlO衬底压缩应变的薄膜中增强了。通过将层厚度减小至三个晶胞并随后进行LaAlO表面终止处理，由于大的声子拖拽（），观察到比块状值增强了10倍，并且对总热电功率的贡献在高达220 K的更宽温度范围内出现。热电功率增强源于晶格振动与压缩应变超薄LaNiO中具有大有效质量的d电子的耦合，并且电子 - 声子相互作用通过从LaAlO衬底和覆盖层的声子泄漏而大大增强。过渡金属氧化物异质结构成为在追求高性能热电材料过程中操纵电子和声子特性的新领域。
