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.
Kagome lattices facilitate various quantum phases, yet in bulk materials, their kagome flat-bands often interact with bulk bands, suppressing kagome electronic characteristics for hosting these phases. Here, we use density-functional-theory calculations to predict the geometric and electronic structures, as well as the topological and magnetic properties, of a series of MoTe2-x kagome monolayers formed by mirror-twin-boundary (MTB) loops. We analyze nine MTB-loop configurations of varying sizes and arrangements to assess their impact on various properties. Within the intrinsic bandgap of MoTe2, we identify two sets of kagome bands, originating from in-plane and out-of-plane Te p-orbitals at MTB-loop edges and -vertices, respectively. Three configurations exhibit superior stability, while three others show comparable stability. Among these, four display bandgaps and potentially non-zero Z2 topological invariants, suggesting possible topological phases, while the remaining two are metallic and feature Stoner magnetization. These findings guide the design of kagome-based two-dimensional materials with tunable electronic, topological, and magnetic properties.
Zemin Pan#, Wenqi Xiong#, Jiaqi Dai#, Hui Zhang#, Yunhua Wang, Tao Jian, Xingxia Cui, Jinghao Deng, Xiaoyu Lin, Zhengbo Cheng, Yusong Bai, Chao Zhu, Da Huo, Geng Li, Min Feng, Jun He, Wei Ji*, Shengjun Yuan*, Fengcheng Wu*, Chendong Zhang*, and Hong-Jun Gao
Abstract:
Although the kagome model is fundamentally two-dimensional, the essential kagome physics, i.e., the kagome-bands-driven emergent electronic states, has yet to be explored in the monolayer limit. Here, we present the experimental realization of kagome physics in monolayer Mo33Te56, showcasing both ferromagnetic ordering and a correlated insulating state with an energy gap of up to 15 meV. Using a combination of scanning tunnelling microscopy and theoretical calculations, we find a structural phase of the monolayer Mo-Te compound, which forms a mirror-twin boundary loop superlattice exhibiting kagome geometry and multiple sets of kagome bands. The partial occupancy of these nearly flat bands results in Fermi surface instability, counteracted by the emergence of ferromagnetic order (with a coercive field ~0.1 T, as observed by spin-polarized STM) and the opening of a correlated hard gap. Our work establishes a robust framework featuring well-defined atomic and band structures, alongside the intrinsic two-dimensional nature, essential for the rigorous examination of kagome physics.
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