Qin Ting-Xiao, You En-Ming, Zhang Jia-Ye, Wang Hai-Long, Zhang Kelvin H L, Mao Bing-Wei, Tian Zhong-Qun
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China.
Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China.
Nano Lett. 2022 Apr 13;22(7):2755-2761. doi: 10.1021/acs.nanolett.1c04698. Epub 2022 Mar 22.
Oxide heterointerfaces with high carrier density can interact strongly with the lattice phonons, generating considerable plasmon-phonon coupling and thereby perturbing the fascinating optical and electronic properties, such as two-dimensional electron gas, ferromagnetism, and superconductivity. Here we use infrared-spectroscopic nanoimaging based on scattering-type scanning near-field optical microscopy (s-SNOM) to quantify the interaction of electron-phonon coupling and the spatial distribution of local charge carriers at the SrTiO/TiO interface. We found an increased high-frequency dielectric constant (ε = 7.1-9.0) and charge carrier density ( = 6.5 × 10 to 1.5 × 10 cm) near the heterointerface. Moreover, quantitative information between the charge carrier density and extension thickness across the heterointerface has been extracted by monochromatic near-field imaging. A direct evaluation of the relationship between the thickness and the interaction of charge carrier-phonon coupling of the heterointerface would provide valuable information for the development of oxide-based electronic devices.
具有高载流子密度的氧化物异质界面能够与晶格声子发生强烈相互作用，产生可观的等离激元 - 声子耦合，进而扰乱诸如二维电子气、铁磁性和超导性等迷人的光学和电子特性。在此，我们基于散射型扫描近场光学显微镜（s - SNOM）使用红外光谱纳米成像技术，来量化 SrTiO/TiO 界面处电子 - 声子耦合的相互作用以及局部电荷载流子的空间分布。我们发现在异质界面附近高频介电常数增加（ε = 7.1 - 9.0）且电荷载流子密度增加（= 6.5 × 10 至 1.5 × 10 cm）。此外，通过单色近场成像提取了异质界面上电荷载流子密度与扩展厚度之间的定量信息。对异质界面厚度与电荷载流子 - 声子耦合相互作用之间关系的直接评估，将为基于氧化物的电子器件的发展提供有价值的信息。
