Zhang Zhi-Hao, Wu Linlu, Miao Mao-Peng, Qin Hao-Jun, Chen Gang, Cai Min, Liu Lixin, Zhu Lan-Fang, Zhang Wenhao, Zhai Tianyou, Ji Wei, Fu Ying-Shuang
School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China.
Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China.
J Am Chem Soc. 2024 Jul 10;146(27):18556-18564. doi: 10.1021/jacs.4c04450. Epub 2024 Jun 29.
Manipulating single electrons at the atomic scale is vital for mastering complex surface processes governed by the transfer of individual electrons. Polarons, composed of electrons stabilized by electron-phonon coupling, offer a pivotal medium for such manipulation. Here, using scanning tunneling microscopy and spectroscopy (STM/STS) and density functional theory (DFT) calculations, we report the identification and manipulation of a new type of polaron, dubbed van der Waals (vdW) polaron, within mono- to trilayer ultrathin films composed of SbO molecules that are bonded via vdW attractions. The SbO films were grown on a graphene-covered SiC(0001) substrate via molecular beam epitaxy. Unlike prior molecular polarons, STM imaging observed polarons at the interstitial sites of the molecular film, presenting unique electronic states and localized band bending. DFT calculations revealed the lowest conduction band as an intermolecular bonding state, capable of ensnaring an extra electron through locally diminished intermolecular distances, thereby forming an intermolecular vdW polaron. We also demonstrated the ability to generate, move, and erase such vdW polarons using an STM tip. Our work uncovers a new type of polaron stabilized by coupling with intermolecular vibrations where vdW interactions dominate, paving the way for designing atomic-scale electron transfer processes and enabling precise tailoring of electron-related properties and functionalities.
在原子尺度上操控单个电子对于掌握由单个电子转移所支配的复杂表面过程至关重要。极化子由通过电子 - 声子耦合稳定的电子组成，为这种操控提供了关键介质。在此，我们利用扫描隧道显微镜和光谱（STM/STS）以及密度泛函理论（DFT）计算，报告了在由通过范德华（vdW）引力结合的SbO分子组成的单层至三层超薄膜中，一种新型极化子即范德华（vdW）极化子的识别与操控。SbO薄膜通过分子束外延生长在覆盖有石墨烯的SiC(0001)衬底上。与先前的分子极化子不同，STM成像在分子薄膜的间隙位置观察到极化子，呈现出独特的电子态和局域能带弯曲。DFT计算揭示最低导带为分子间键合态，能够通过局部减小分子间距离捕获一个额外电子，从而形成分子间vdW极化子。我们还展示了使用STM针尖生成、移动和擦除此类vdW极化子的能力。我们的工作揭示了一种通过与以vdW相互作用为主导的分子间振动耦合而稳定的新型极化子，为设计原子尺度的电子转移过程以及实现对电子相关性质和功能的精确调控铺平了道路。
