Article
Nanoscience & Nanotechnology
Kang Wang, Takashi Taniguchi, Kenji Watanabe, Jiamin Xue
Summary: Two-dimensional semiconductors show great potential as channel materials for field-effect transistors. Unlike traditional three-dimensional semiconductors, their surface with saturated chemical bonds maintains excellent properties even at monolayer thickness. However, the edges of these materials, which often go unnoticed, have important effects on devices. This study demonstrates that the edges of exfoliated and etched MoS2 are naturally p-type doped and can form p-n junctions with the bulk of the flake, which can be utilized to create rectifying or optoelectronic devices without the need for external doping.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Han Yang, Teng Zhang, Zeping Huang, Yaoyao Chen, Xuan Song, Xiaoyu Hao, Huixia Yang, Xu Wu, Yu Zhang, Liwei Liu, Hong-Jun Gao, Yeliang Wang
Summary: This study reports the nanoscale structural reconstruction and induced electronic properties at the atomically sharp edge of a CDW correlated insulator 1T-NbSe2. The CDW unit cells at the edge evolve from bulk CDW order and reconstruct into a quartet structure spontaneously. An anomalous electronic superstructure with a periodicity four times that of ordinary CDW lattice is observed along the edge, providing a new way to design one-dimensional electronic superstructures in 2D quantum materials.
Article
Chemistry, Physical
Minjiang Dan, Gongwei Hu, Lijie Li, Yan Zhang
Summary: A high performance quantum piezotronic tunneling transistor based on edge states in MoS2 nanoribbon device architecture is demonstrated at room temperature. The study reveals that the tunneling current can be exponentially controlled by the piezotronic effect, and the Schottky barrier height can also be modified. The strain sensitivity of the quantum piezotronic transistor is found to be over 10^3. This research has significant implications for the design of new generation transistor devices and opens up possibilities for high performance quantum piezotronic devices at room temperature.
Article
Chemistry, Multidisciplinary
Xinzuo Sun, Yan Chen, Dongyang Zhao, Takashi Taniguchi, Kenji Watanabe, Jianlu Wang, Jiamin Xue
Summary: This study demonstrates the significant modulation of the band structure of few-layer MoS2 using a ferroelectric P(VDF-TrFE) gate. The fully polarized P(VDF-TrFE) gate creates an electric field of up to 0.62 V/nm through the MoS2 layers, which greatly affects the band structure. The experimental results show a strong band bending effect and an enlarged energy separation between quantum-well subbands. This study intuitively showcases the potential of ferroelectric gates in manipulating the band structure of 2D materials.
Article
Chemistry, Multidisciplinary
Kalyan Biswas, Jose I. Urgel, M. R. Ajayakumar, Ji Ma, Ana Sanchez-Grande, Shayan Edalatmanesh, Koen Lauwaet, Pingo Mutombo, Jose M. Gallego, Rodolfo Miranda, Pavel Jelinek, Xinliang Feng, David Ecija
Summary: This study reports the successful on-surface synthesis of the largest pristine member of the n-PA family, peri-heptacene, on an Au(111) substrate under ultra-high vacuum conditions. High-resolution scanning tunneling microscopy and theoretical simulations provide insights into the chemical structure of this previously elusive compound. Scanning tunneling spectroscopy reveals that peri-heptacene exhibits an antiferromagnetic open-shell singlet ground state and a singlet-triplet spin-flip inelastic excitation with an effective exchange coupling of 49 meV.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Huimin Zhang, Qiang Zou, Lian Li
Summary: The study revealed the presence of helical edge states in FeSe multilayer films, with density of states following a power law characteristic of Tomonaga-Luttinger liquid, and corresponding Luttinger parameters of 0.26 and 0.43 at the {100}Se and {110}Se edges respectively. These results demonstrate strong correlations and nontrivial excitations in FeSe, providing insights into topological properties and novel phenomena in helical edge channels.
Article
Multidisciplinary Sciences
Xiaohu Zheng, Qiangqiang Gu, Yiyuan Liu, Bingbing Tong, Jian-Feng Zhang, Chi Zhang, Shuang Jia, Ji Feng, Rui-Rui Du
Summary: Scanning tunneling spectroscopy revealed the signature of Fermi arcs on the 1D ledges of a Weyl semimetal's surfaces, showcasing the bulk-boundary correspondence principle in action even at atomic scales. The study demonstrated the extreme robustness of this principle in providing topological protection for Fermi arcs, allowing for potential applications in miniaturized quantum devices.
NATIONAL SCIENCE REVIEW
(2022)
Article
Nanoscience & Nanotechnology
Thais Chagas, Guilherme A. S. Ribeiro, Barbara L. T. Rosa, Danial Bahrami, Arman Davtyan, Rafael R. Barreto, Juan C. Gonzalez, Rogerio Magalhaes-Paniago, Angelo Malachias
Summary: In this study, the researchers investigated the structural and electronic properties of Mg-doped GaAs(111) nanowires, revealing conducting Ga2Mg/Mg clusters on the lateral surfaces, enabling electrical contacts with reduced Schottky barriers. Density functional theory was used to investigate the electronic response of Ga2Mg, showing metallic behavior at room temperature and quantum confinement at low temperatures.
ACS APPLIED NANO MATERIALS
(2021)
Article
Physics, Condensed Matter
Keisuke Sagisaka, Tomoko Kusawake, David Bowler, Shinya Ohno
Summary: The electronic properties of the surface of beta-FeSi2 were studied using scanning tunnelling microscopy (STM) and spectroscopy (STS) with density functional theory calculations. The STM simulations reproduced the experimental images, while the STS revealed metallic surface states as predicted by theory. The Fermi level was pinned by a surface state within the band gap of beta-FeSi2, regardless of substrate polarity. An energy gap in the unoccupied surface states of beta-FeSi2 was observed, resulting in negative differential conductance at approximately 0.45 eV above the Fermi level in STS measurements at 4.5 K.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Hao-Ke Xu, Mingqiang Gu, Fucong Fei, Yi-Sheng Gu, Dang Liu, Qiao-Yan Yu, Sha-Sha Xue, Xu-Hui Ning, Bo Chen, Hangkai Xie, Zhen Zhu, Dandan Guan, Shiyong Wang, Yaoyi Li, Canhua Liu, Qihang Liu, Fengqi Song, Hao Zheng, Jinfeng Jia
Summary: Research has discovered that MnBi4Te7 is a topological insulator with quantum anomalous Hall effect and axion insulator phase. Through scanning tunneling spectroscopy, it has been observed that there is an electronic state at the edge of the magnetic MnBi2Te4 layer at 4.5 K, but not in the nonmagnetic Bi2Te3 layer. As the temperature increases, the edge state disappears, while the state induced by point defects persists.
Article
Chemistry, Multidisciplinary
Chao Li, Jan Homberg, Alexander Weismann, Richard Berndt
Summary: The study reveals that AlPc molecules lose their spin moment on superconducting Pb(100) but molecular magnetism can be restored by surrounding molecules. Unlike other molecules, AlPc molecules have similar magnetic moments and lead to unusually high conductance peaks.
Article
Chemistry, Physical
Gonglei Shao, Meiqing Yang, Haiyan Xiang, Song Luo, Xiong-Xiong Xue, Huimin Li, Xu Zhang, Song Liu, Zhen Zhou
Summary: This study investigates the layer-dependent properties of 2D vertical heterostructures and demonstrates the tunable band alignment and enhanced electrical conductivity in β-In2Se3/MoS2 heterostructures. The edge reconstruction and conductive layers play decisive roles in optimizing electron energy levels and improving catalytic performance.
Article
Chemistry, Multidisciplinary
Linghao Yan, Orlando J. Silveira, Benjamin Alldritt, Ondrej Krejci, Adam S. Foster, Peter Liljeroth
Summary: The successful fabrication of a 2D monolayer Cu-dicyanoanthracene MOF on an epitaxial graphene surface with long-range order and the study of its structural and electronic properties using low-temperature scanning tunneling microscopy and spectroscopy, along with density-functional theory calculations, show promise for future applications in electronic devices. The ability to access multiple molecular charge states in the 2D MOF using tip-induced local electric fields suggests potential for fabricating and characterizing 2D MOFs with engineered electronic states.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Yi-Ying Sung, Harmina Vejayan, Christopher J. Baddeley, Neville V. Richardson, Federico Grillo, Renald Schaub
Summary: On-surface synthesis with designer precursor molecules is an effective method for preparing graphene nanoribbons (GNRs) with tunable electronic properties. The band gap of GNRs doped with heteroatoms remains unchanged, but hydrogenation can engineer a tunable band gap. Surface-confined hydrogenation studies on 7-armchair GNRs grown on Au(111) surfaces reveal a self-limited hydrogenation process. The electronic properties of the GNR/Au(111) system can be modified by edge and basal-plane hydrogenation, and a mechanism for the hydrogenation process is proposed.
Article
Chemistry, Multidisciplinary
Niklas Friedrich, Rodrigo E. Menchon, Iago Pozo, Jeremy Hieulle, Alessio Vegliante, Jingcheng Li, Daniel Sanchez-Portal, Diego Pena, Aran Garcia-Lekue, Jose Ignacio Pascual
Summary: Spin-hosting graphene nanostructures offer potential for metal-free elementary quantum spintronic devices. In this study, a narrow graphene nanoribbon doped with boron heteroatoms was fabricated and exhibited metallic behavior with localized spin 1/2 states. The transport measurements and conductance spectra confirmed the presence of localized spin states in the nanoribbon. Density functional theory analysis explained the metallic character and spin localization due to the boron atoms. This research opens up possibilities for electronic addressing and controlling carbon spins in real device architectures.
