Zhi-Hao Li#, Jia-Qi Dai#, Guan Luo, Ruo-Ning Li, An-Jing Zhao, Jun-Jie Duan, Yu Ge, Zi-Cong Wang, Wei Ji*, Ting Chen*, Dong Wang and Li-Jun Wan
Abstract:
Atomically thin InTe, a III–VI analogue of InSe, has recently emerged as a promising two-dimensional semiconductor for nanoelectronics, yet the nature of its two-dimensional electron gas (2DEG) has remained experimentally elusive. Here, using scanning tunneling microscopy (STM) combined with quasiparticle interference (QPI) imaging, we present direct evidence of the existence of a 2DEG in monolayer and bilayer InTe. Bias-dependent standing-wave patterns reveal a parabolic conduction-band dispersion in both thicknesses. Quantitative analysis yields a low electron effective mass of 0.241me in monolayer InTe, smaller than that of monolayer InSe/BLG (∼0.27me). In bilayer InTe, interlayer coupling lifts the conduction-band-edge degeneracy, and produces two subbands with effective masses of 0.197me and 0.802me. Density functional theory calculations are in good agreement with the experimental observations. These results establish atomically thin InTe as a promising platform for low-dimensional electronic physics and nanoelectronic applications.
Zhi-Hao Li#, Jia-Qi Dai#, Guan Luo, Ruo-Ning Li, An-Jing Zhao, Jun-Jie Duan, Yu Ge, Zi-Cong Wang, Wei Ji*, Ting Chen*, Dong Wang and Li-Jun Wan
Abstract:
As a fundamental phenomenon in nature, chirality has been extensively studied in molecular structures; however, it remains underexplored at the electronic level. Understanding how structural chirality transfers into electronic states is crucial for uncovering the essence of many chiral effects. In this study, we report the engineering and direct visualization of chiral electronic states within an otherwise planar, achiral hexa- peri -hexabenzocoronene (HBC) framework. By employing atomically precise asymmetric nitrogen doping of HBC through on-surface synthesis, we fabricate a C3 -symmetric triaza-HBC on Au(111). Utilizing high-resolution scanning tunneling microscopy and non-contact atomic force microscopy, we resolve the chiral molecular structure of triaza-HBC confined to the surface, as well as the chiral texture of the resulting interfacial electronic states and its evolution at different energies. Density functional theory calculations reveal that these electronic chiral features arise from the molecule’s intrinsic chiral orbitals, which hybridize strongly with the metal substrate while still retaining their chiral character. This study not only demonstrates a clear transfer of chirality from molecular structure to the electronic landscape but also provides a versatile platform for the rational design of chiral electronic molecules and materials.
Manyu Wang, Chang Li, Bingxian Shi, Shuo Mi, Xiaoxiao Pei, Shumin Meng, Yanyan Geng, Fei Pang, Rui Xu, Li Huang, Wei Ji, Hong-Jun Gao, Peng Cheng*, Le Lei*, and Zhihai Cheng*
Abstract:
Controlling mesoscale and nanoscale material structures and properties through self-organized atomic behavior is essential for atomic-scale manufacturing. However, direct and visual studies of the cross-scale effects of such atomic self-organization on mesoscopic structures remain scarce. Herein, we report the intertwined atomic-nanoscale-mesoscale structures via the intralayer Fe-chains in the sandwich-like layered FePd2Te2 crystal by scanning tunneling microscopy (STM) and atomic force microscopy (AFM). The hierarchical orthogonal corrugated morphologies are directly revealed and attributed to their chain-orientation-determined twinning-domain effect. Both Fe-chains of the middle-sublayer and two kinds of Te atoms of the top-sublayer are further atomically resolved, indicating the critical effects of Pd atoms/voids on the intralayer anisotropic Fe-chains and the interlayer structural alignment. The thermally induced and strain-related structural transitions of the surface layer are further investigated and discussed based on the proposed filling model of Pd-voids by the intralayer Pd atoms. Our work not only provides a deep understanding of this exotic layered magnetic material but also will inspire more perspectives for tailoring its anisotropic atomic-to-mesoscale structures and properties.
Quantum interference has been intensively pursued in molecular electronics to investigate and utilize coherent electron transport at the ultra-small level. An essential type of quantum interference with drastic destructive-constructive switching, known as Fano interference, has been widely reported in various kinds of nanoelectronics electronic systems, but not yet been electrostatically gating in a single-molecule device. Here, we fabricate the three-terminal single-molecule transistors based on the molecule with a long backbone and a side group to demonstrate the gate-controllable Fano interference. By applying bias and gate voltages, the two-dimensional differential conductance map shows the noncentrosymmetrical Fano patterns. Combined with the electron transport model and the first principles calculations, the resonant parameters of the Fano interference can unveil the coupling geometry of the junction and the spatial distribution of the resonant states. Our findings provide an instrumental method to induce and utilize the quantum interference behaviours at the molecular level.
Haohan Li, Mykola Telychko, Linwei Zhou, Zhi Chen, Xinnan Peng, Wei Ji, Jiong Lu & Kian Ping Loh
Abstract
Formation of a two-dimensional (2D) supramolecular self-assembly and a 2D organometallic framework derived from a brominated N-heterocyclic aromatic molecule (4Br-TAP) on Au(111) and Ag(111) substrates were studied using chemical bond-resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (ncAFM) techniques combined with density functional theory (DFT) calculations. The 4Br-TAP-based 2D molecular framework on Au(111) is constructed by diverse Br···Br and Br···N noncovalent interactions, which are resolved with sub-angstrom resolution using combined STM and ncAFM imaging with a CO-functionalized tip and further quantified using DFT calculations. The distortion of molecular backbones, triggered by a highly nonuniform bonding environment, leads to lifting of the degeneracy of the intrinsic resonance structures of tetraazapyrene (TAP) moieties and emergence of two chiral Kekulé-like structures. In contrast, debromination of 4Br-TAP on Ag(111) leads to the formation of an ordered 2D organometallic framework linked by C–Ag–C bonds. Our results underpin the tremendous potential of the tip-functionalized ncAFM technique for microscopic identification of a complex interplay of intermolecular interactions and their associated impact on the molecular resonance structures.
You must be logged in to post a comment.