Department of Physics, University of California at Berkeley, Berkeley, CA, 94720, USA.
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Nat Commun. 2019 Jan 29;10(1):477. doi: 10.1038/s41467-019-08371-2.
The photon-like behavior of electrons in graphene causes unusual confinement properties that depend strongly on the geometry and strength of the surrounding potential. We report bottom-up synthesis of atomically-precise one-dimensional (1D) arrays of point charges on graphene that allow exploration of a new type of supercritical confinement of graphene carriers. The arrays were synthesized by arranging FTCNQ molecules into a 1D lattice on back-gated graphene, allowing precise tuning of both the molecular charge and the array periodicity. While dilute arrays of ionized FTCNQ molecules are seen to behave like isolated subcritical charges, dense arrays show emergent supercriticality. In contrast to compact supercritical clusters, these extended arrays display both supercritical and subcritical characteristics and belong to a new physical regime termed "frustrated supercritical collapse". Here carriers in the far-field are attracted by a supercritical charge distribution, but their fall to the center is frustrated by subcritical potentials in the near-field, similar to trapping of light by a dense cluster of stars in general relativity.
在石墨烯中，电子呈现类光子行为，这导致其具有异常的约束特性，这些特性强烈依赖于周围势的几何形状和强度。我们报告了在石墨烯上自下而上合成原子级精度的点电荷一维（1D）阵列，这使得人们能够探索石墨烯载流子的一种新型超临界约束。这些阵列是通过将 FTCNQ 分子排列成背栅石墨烯上的一维晶格来合成的，这允许精确调整分子电荷和阵列的周期性。虽然稀疏散列的电离 FTCNQ 分子表现为孤立的亚临界电荷，但密集的阵列则表现出突现的超临界性。与紧凑的超临界团簇不同，这些扩展的阵列同时显示出超临界和亚临界特性，属于一种新的物理状态，称为“受挫超临界崩塌”。在这里，远场中的载流子被超临界电荷分布所吸引，但它们向中心的下降被近场中的亚临界势所阻碍，类似于广义相对论中密集星团对光的捕获。
