在原子尺度上操纵单个电子对于掌握由单个电子转移控制的复杂表面过程至关重要。极化子由电子-声子耦合稳定的电子组成，为这种操作提供了关键介质。
该文中，使用扫描隧道显微镜和光谱学（STM/STS）以及密度泛函理论（DFT）计算，研究人员报道了一种新型极化子的识别和操作，该极化子被称为范德华极化子（vdW），位于由Sb2O3分子通过vdW吸引结合而成的单层到三层超薄膜中。通过分子束外延在石墨烯覆盖的SiC（0001）衬底上生长Sb2O3膜。
与先前的分子极化子不同，STM成像在分子膜的间隙位置观察到极化子，呈现出独特的电子态和局部的能带弯曲。DFT计算揭示了最低导带作为分子间键合态，能够通过局部减小的分子间距离包裹额外的电子，从而形成分子间vdW极化子。研究人员还展示了使用STM尖端产生、移动和擦除这种vdW极化子的能力。
该工作揭示了一种新型的极化子，它通过与分子间振动耦合来稳定，其中vdW相互作用占主导地位，为设计原子级电子转移过程和实现电子相关性质和功能的精确定制铺平了道路。
附：英文原文
Title: Discovery and Manipulation of van der Waals Polarons in Sb2O3 Ultrathin Molecular Crystal
Author: Zhi-Hao Zhang, Linlu Wu, Mao-Peng Miao, Hao-Jun Qin, Gang Chen, Min Cai, Lixin Liu, Lan-Fang Zhu, Wenhao Zhang, Tianyou Zhai, Wei Ji, Ying-Shuang Fu
Issue&Volume: June 29, 2024
Abstract: 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 Sb2O3 molecules that are bonded via vdW attractions. The Sb2O3 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.
DOI: 10.1021/jacs.4c04450
