1
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Quan W, Lu Y, Wu Q, Cheng Y, Hu J, Zhang Z, Wang J, Li Z, Wang L, Ji Q, Zhang Y. Substantial Energy Band Modulation of Semiconducting Hexagonal GaTe Quantum Wells by Layer Thickness and Mirror Twin Boundaries. ACS NANO 2024. [PMID: 39074911 DOI: 10.1021/acsnano.4c05858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/31/2024]
Abstract
Exploring emerging two-dimensional (2D) van der Waals (vdW) semiconducting materials and precisely tuning their electronic properties at the atomic level have long been recognized as crucial issues for developing their high-end electronic and optoelectronic applications. As a III-VI semiconductor, ultrathin layered hexagonal GaTe (h-GaTe) remains unexplored in terms of its intrinsic electronic properties and band engineering strategies. Herein, we report the successful synthesis of ultrathin h-GaTe layers on a selected graphene/SiC(0001) substrate, via molecular beam epitaxy (MBE). The widely tunable quasiparticle band gaps (∼2.60-1.55 eV), as well as the vdW quantum well states (QWSs) that can be strictly counted by the layer numbers, are well characterized by onsite scanning tunneling microscopy/spectroscopy (STM/STS), and their origins are clearly addressed by density functional theory (DFT) calculations. More intriguingly, distinctive 8|8E and 4|4P (Ga) mirror twin boundaries (MTBs) are identified in the ultrathin h-GaTe flakes, which can induce decreased band gaps and prominent p-doping effects. This work should deepen our understanding on the electronic tunability of 2D III-VI semiconductors by thickness control and line defect engineering, which may hold promise for fabricating atomic-scale vertical and lateral homojunctions toward ultrascaled electronics and optoelectronics.
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Affiliation(s)
- Wenzhi Quan
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Yue Lu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Qilong Wu
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Yujin Cheng
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Jingyi Hu
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Zehui Zhang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Jialong Wang
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
| | - Zhenzhu Li
- Department of Materials, Imperial College London, London SW7 2AZ, U.K
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Qingqing Ji
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Yanfeng Zhang
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China
- School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China
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2
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Koroteev YM, Silkin IV, Silkin VM, Chulkov EV. Quantum-Size Effects in Ultra-Thin Gold Films on Pt(111) Surface. MATERIALS (BASEL, SWITZERLAND) 2023; 17:63. [PMID: 38203917 PMCID: PMC10779727 DOI: 10.3390/ma17010063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 12/15/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024]
Abstract
We calculate, within the density-functional theory, the atomic and electronic structure of the clean Pt(111) and Au(111) surfaces and the nML-Au/Pt(111) systems with n varying from one to three. The effect of the spin-orbital interaction was taken into account. Several new electronic states with strong localization in the surface region were found and discussed in the case of clean surfaces. The Au adlayers introduce numerous quantum well states in the energy regions corresponding to the projected bulk band continuum of Au(111). Moreover, the presence of states resembling the true Au(111) surface states can be detected at n = 2 and 3. The Au/Pd interface states are found as well. In nML-Au/Pt(111), the calculated work function presents a small variation with a variation of the number of the Au atomic layer. Nevertheless, the effect is significantly smaller in comparison to the s-p metals.
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Affiliation(s)
- Yury M. Koroteev
- Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Sciences, 634055 Tomsk, Russia
- Laboratory of Electronic and Spin Structure of Nanosystems, Saint Petersburg State University, 198504 Saint Petersburg, Russia
| | - Igor V. Silkin
- Faculty of Physics, Tomsk State University, 634050 Tomsk, Russia
| | - Vyacheslav M. Silkin
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco (UPV-EHU), Apdo. 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center (DIPC), P. Manuel Lardizabal 4, 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, Pl. Euskadi 5, 48009 Bilbao, Spain
| | - Evgueni V. Chulkov
- Laboratory of Electronic and Spin Structure of Nanosystems, Saint Petersburg State University, 198504 Saint Petersburg, Russia
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco (UPV-EHU), Apdo. 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center (DIPC), P. Manuel Lardizabal 4, 20018 San Sebastián, Spain
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, P. Manuel Lardizabal 5, 20018 San Sebastián, Spain
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3
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Wang Y, Gao Q, Li W, Cheng P, Zhang YQ, Feng B, Hu Z, Wu K, Chen L. Nearly Ideal Two-Dimensional Electron Gas Hosted by Multiple Quantized Kronig-Penney States Observed in Few-Layer InSe. ACS NANO 2022; 16:13014-13021. [PMID: 35943244 DOI: 10.1021/acsnano.2c05556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A theoretical ideal two-dimensional electron gas (2DEG) was characterized by a flat density of states independent of energy. Compared with conventional two-dimensional free-electron systems in semiconductor heterojunctions and noble metal surfaces, we report here the achievement of ideal 2DEG with multiple quantized states in few-layer InSe films. The multiple quantum well states (QWSs) in few-layer InSe films are found, and the number of QWSs is strictly equal to the number of atomic layers. The multiple stair-like DOS as well as multiple bands with parabolic dispersion both characterize ideal 2DEG features in these QWSs. Density functional theory calculations and numerical simulations based on quasi-bounded square potential wells described as the Kronig-Penney model provide a consistent explanation of 2DEG in the QWSs. Our work demonstrates that 2D van der Waals materials are ideal systems for realizing 2DEG hosted by multiple quantized Kronig-Penney states, and the semiconducting nature of the material provides a better chance for construction of high-performance electronic devices utilizing these states, for example, superlattice devices with negative differential resistance.
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Affiliation(s)
- Yu Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Qian Gao
- School of Physics, Nankai University, Tianjin 300071, China
| | - Wenhui Li
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Peng Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yi-Qi Zhang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Baojie Feng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Zhenpeng Hu
- School of Physics, Nankai University, Tianjin 300071, China
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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4
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Cheng P, Kong L, Zhang T, Liu H, Fu H, Chen L, Wu K, Chen X, Meng S, Xue QK. In-Situ Manipulation of the Magnetic Anisotropy of Single Mn Atom via Molecular Ligands. NANO LETTERS 2021; 21:3566-3572. [PMID: 33830782 DOI: 10.1021/acs.nanolett.1c00545] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Magnetic anisotropy is essential for permanent magnets to maintain their magnetization along specific directions. Understanding and controlling the magnetic anisotropy on a single-molecule scale are challenging but of fundamental importance for the future's spintronic technology. Here, by using scanning tunneling microscopy (STM), we demonstrated the ability to control the magnetic anisotropy by tuning the ligand field at the single-molecule level. We constructed a molecular magnetic complex with a single Mn atom and an organic molecule (4,4'-biphenyldicarbonitrile) as a ligand via atomic manipulation. Inelastic tunneling spectra (IETS) show that the Mn complex has much larger axial magnetic anisotropy than individual Mn atoms, and the anisotropy energy can be tuned by the coupling strength of the ligand. With density functional theory calculations, we revealed that the enhanced magnetic anisotropy of Mn arising from the carbonitrile ligand provides a prototype for the engineering of the magnetism of quantum devices.
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Affiliation(s)
- Peng Cheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Longjuan Kong
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
| | - Tong Zhang
- State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200438, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Hang Liu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
| | - Huixia Fu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
| | - Lan Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kehui Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xi Chen
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Sheng Meng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
| | - Qi-Kun Xue
- Department of Physics, Tsinghua University, Beijing 100084, China
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5
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Montemore MM, van Spronsen MA, Madix RJ, Friend CM. O2 Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts. Chem Rev 2017; 118:2816-2862. [DOI: 10.1021/acs.chemrev.7b00217] [Citation(s) in RCA: 230] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthew M. Montemore
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, Massachusetts 02138, United States
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, Massachusetts 02138, United States
| | - Matthijs A. van Spronsen
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, Massachusetts 02138, United States
| | - Robert J. Madix
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, Massachusetts 02138, United States
| | - Cynthia M. Friend
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St, Cambridge, Massachusetts 02138, United States
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford St, Cambridge, Massachusetts 02138, United States
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6
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Cai W, Zhang S, Lv J, Chen J, Yang J, Wang Y, Guo X, Peng L, Ding W, Chen Y, Lei Y, Chen Z, Yang W, Xie Z. Nanotubular Gamma Alumina with High-Energy External Surfaces: Synthesis and High Performance for Catalysis. ACS Catal 2017. [DOI: 10.1021/acscatal.7b00080] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Weimeng Cai
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Shengen Zhang
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Jiangang Lv
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Junchao Chen
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Jie Yang
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Yibo Wang
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Xuefeng Guo
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Luming Peng
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Weiping Ding
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Yi Chen
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Yanhua Lei
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
- Department
of Physics, South University of Science and Technology of China, Shenzhen 518055, China
| | - Zhaoxu Chen
- Lab
of Mesoscopic Chemistry, Department of Chemistry, Nanjing University, Nanjing 210093, China
| | - Weimin Yang
- Sinopec Shanghai Research Institute Petrolchemical Technology, Shanghai 201208, China
| | - Zaiku Xie
- Sinopec Shanghai Research Institute Petrolchemical Technology, Shanghai 201208, China
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7
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Liu X, Wang CZ. Interplay between quantum confinement and surface effects in thickness selective stability of thin Ag and Eu films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:185504. [PMID: 28272026 DOI: 10.1088/1361-648x/aa6556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using first-principles calculations, we show that both face-centered cubic (fcc) Ag (1 1 0) ultrathin films and body-centered cubic (bcc) Eu(1 1 0) ultrathin films exhibit thickness selective stability. However, the origin of such thickness selection is different. While the thickness selective stability in fcc Ag(1 1 0) films is mainly due to the well-known quantum well states ascribed to the quantum confinement effects in free-electron-like metal films, the thickness selection in bcc Eu(1 1 0) films is more complex and also strongly correlated with the occupation of the surface and surface resonance states.
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Affiliation(s)
- Xiaojie Liu
- Center for Quantum Sciences and School of Physics, Northeast Normal University, Changchun 130117, People's Republic of China
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8
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Li C, Yi S, Xia C, Cui P, Niu C, Cho JH, Jia Y, Zhang Z. Dimensionality and Valency Dependent Quantum Growth of Metallic Nanostructures: A Unified Perspective. NANO LETTERS 2016; 16:6628-6635. [PMID: 27685453 DOI: 10.1021/acs.nanolett.6b03351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantum growth refers to the phenomena in which the quantum mechanically confined motion of electrons in metallic wires, islands, and films determines their overall structural stability as well as their physical and chemical properties. Yet to date, there has been a lack of a unified understanding of quantum growth with respect to the dimensionality of the nanostructures as well as the valency of the constituent atoms. Based on a first-principles approach, we investigate the stability of nanowires, nanoislands, and ultrathin films of prototypical metal elements. We reveal that the Friedel oscillations generated at the edges (or surfaces) of the nanostructures cause corresponding oscillatory behaviors in their stability, leading to the existence of highly preferred lengths (or thicknesses). Such magic lengths of the nanowires are further found to depend on both the number of valence electrons and the radial size, with the oscillation period monotonously increasing for alkali and group IB metals, and monotonously decreasing for transition and group IIIA-VA metals. When the radial size of the nanowires increases to reach ∼10 Å, the systems equivalently become nanosize islands, and the oscillation period saturates to that of the corresponding ultrathin films. These findings offer a generic perspective of quantum growth of different classes of metallic nanostructures.
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Affiliation(s)
- Chenhui Li
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University , Zhengzhou 450001, China
| | - Seho Yi
- Department of Physics and Research Institute for Natural Sciences, Hanyang University , 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea
| | - Congxin Xia
- College of Physics and Materials Science, Henan Normal University , Xinxiang 453000, China
| | - Ping Cui
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Chunyao Niu
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University , Zhengzhou 450001, China
| | - Jun-Hyung Cho
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University , Zhengzhou 450001, China
- Department of Physics and Research Institute for Natural Sciences, Hanyang University , 17 Haengdang-Dong, Seongdong-Ku, Seoul 133-791, Korea
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
| | - Yu Jia
- International Laboratory for Quantum Functional Materials of Henan, and School of Physics and Engineering, Zhengzhou University , Zhengzhou 450001, China
- Key Laboratory for Special Functional Materials of Ministry of Education, and School of Physics and Electronics, Henan University , Kaifeng 475004, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), Hefei National Laboratory for Physical Sciences at the Microscale, and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China , Hefei, Anhui 230026, P. R. China
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9
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Müller M, Néel N, Crampin S, Kröger J. Lateral Electron Confinement with Open Boundaries: Quantum Well States above Nanocavities at Pb(111). PHYSICAL REVIEW LETTERS 2016; 117:136803. [PMID: 27715132 DOI: 10.1103/physrevlett.117.136803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 06/06/2023]
Abstract
We have studied electron states present at the Pb(111) surface above Ar-filled nanocavities created by ion beam irradiation and annealing. Vertical confinement between the parallel crystal and nanocavity surfaces creates a series of quantum well state subbands. Differential conductance data measured by scanning tunneling spectroscopy contain a characteristic spectroscopic fine structure within the highest occupied subband, revealing additional quantization. Unexpectedly, reflection at the open boundary where the thin Pb film recovers its bulk thickness gives rise to the lateral confinement of electrons.
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Affiliation(s)
- M Müller
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
| | - S Crampin
- Department of Physics, University of Bath, Bath BA2 7AY, United Kingdom
| | - J Kröger
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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10
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Hu ZY, Lu H, Zhang SL, Zeng HB. Influences of the Pb 6s 2 lone pair effect and quantum size effect on the diffusion of oxygen atoms on Pb(111) films. RSC Adv 2016. [DOI: 10.1039/c6ra12888b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Based on our previous studies revealing quantum oscillations in the adsorption energetics of atomic oxygen on Pb(111) films, here we study all the possible on-surface and subsurface adsorption sites of oxygen atoms on Pb(111) films at different coverages.
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Affiliation(s)
- Zi-Yu Hu
- Beijing Computational Science Research Center
- Beijing 100193
- People's Republic of China
| | - Hao Lu
- College of Science
- Beijing University of Chemical Technology
- Beijing
- People's Republic of China
| | - Sheng-Li Zhang
- School of Materials Science and Engineering
- Institute of Optoelectronics & Nanomaterials
- Nanjing University of Science and Technology
- Nanjing
- People's Republic of China
| | - Hai-Bo Zeng
- School of Materials Science and Engineering
- Institute of Optoelectronics & Nanomaterials
- Nanjing University of Science and Technology
- Nanjing
- People's Republic of China
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11
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Han Y, Evans JW. Directing Anisotropic Assembly of Metallic Nanoclusters by Exploiting Linear Trio Interactions and Quantum Size Effects: Au Chains on Ag(100) Thin Films. J Phys Chem Lett 2015; 6:2194-2199. [PMID: 26266591 DOI: 10.1021/acs.jpclett.5b00636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Discovery and understanding of mechanisms for kinetically controlled growth of metal nanoclusters can be enabled by realistic atomistic-level modeling with ab initio kinetics. KMC simulation of such a model for Au deposition on Ag(100) films reveals the formation of single-atom-wide Au chains below 275 K, even though 2D islands are thermodynamically preferred. Chain formation is shown to reflect a combination of strong linear trio attractions guiding assembly and a weak driving force and slow rate of transformation of 1D chains to 2D islands (or sometimes irreversible rounding of adatoms from chain sides to ends). Behavior can also be tuned by quantum size effects: chain formation predominates on 2-monolayer Ag(100) films supported on NiAl(100) at 250 K for low coverages but not on 1- or 3-monolayer films, and longer chains form than on bulk Ag(100). Our predictive kinetic modeling shows the potential for simulation-guided discovery and analysis of novel self-assembly processes.
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Affiliation(s)
- Yong Han
- Department of Physics and Astronomy, and Division of Chemical and Biological Sciences, Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, United States
| | - James W Evans
- Department of Physics and Astronomy, and Division of Chemical and Biological Sciences, Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, United States
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12
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Jiang P, Bao X, Salmeron M. Catalytic reaction processes revealed by scanning probe microscopy. [corrected]. Acc Chem Res 2015; 48:1524-31. [PMID: 25856470 DOI: 10.1021/acs.accounts.5b00017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Heterogeneous catalysis is of great importance for modern society. About 80% of the chemicals are produced by catalytic reactions. Green energy production and utilization as well as environmental protection also need efficient catalysts. Understanding the reaction mechanisms is crucial to improve the existing catalysts and develop new ones with better activity, selectivity, and stability. Three components are involved in one catalytic reaction: reactant, product, and catalyst. The catalytic reaction process consists of a series of elementary steps: adsorption, diffusion, reaction, and desorption. During reaction, the catalyst surface can change at the atomic level, with roughening, sintering, and segregation processes occurring dynamically in response to the reaction conditions. Therefore, it is imperative to obtain atomic-scale information for understanding catalytic reactions. Scanning probe microscopy (SPM) is a very appropriate tool for catalytic research at the atomic scale because of its unique atomic-resolution capability. A distinguishing feature of SPM, compared to other surface characterization techniques, such as X-ray photoelectron spectroscopy, is that there is no intrinsic limitation for SPM to work under realistic reaction conditions (usually high temperature and high pressure). Therefore, since it was introduced in 1981, scanning tunneling microscopy (STM) has been widely used to investigate the adsorption, diffusion, reaction, and desorption processes on solid catalyst surfaces at the atomic level. STM can also monitor dynamic changes of catalyst surfaces during reactions. These invaluable microscopic insights have not only deepened the understanding of catalytic processes, but also provided important guidance for the development of new catalysts. This Account will focus on elementary reaction processes revealed by SPM. First, we will demonstrate the power of SPM to investigate the adsorption and diffusion process of reactants on catalyst surfaces at the atomic level. Then the dynamic processes, including surface reconstruction, roughening, sintering, and phase separation, studied by SPM will be discussed. Furthermore, SPM provides valuable insights toward identifying the active sites and understanding the reaction mechanisms. We also illustrate here how both ultrahigh vacuum STM and high pressure STM provide valuable information, expanding the understanding provided by traditional surface science. We conclude with highlighting remarkable recent progress in noncontact atomic force microscopy (NC-AFM) and inelastic electron tunneling spectroscopy (IETS), and their impact on single-chemical-bond level characterization for catalytic reaction processes in the future.
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Affiliation(s)
- Peng Jiang
- State
Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xinhe Bao
- State
Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Miquel Salmeron
- Materials
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Materials Science and Engineering, University of California, Berkeley, California 94720, United States
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13
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Abstract
Abstract
Catalysis, as a key and enabling technology, plays an increasingly important role in fields ranging from energy, environment and agriculture to health care. Rational design and synthesis of highly efficient catalysts has become the ultimate goal of catalysis research. Thanks to the rapid development of nanoscience and nanotechnology, and in particular a theoretical understanding of the tuning of electronic structure in nanoscale systems, this element of design is becoming possible via precise control of nanoparticles’ composition, morphology, structure and electronic states. At the same time, it is important to develop tools for in situ characterization of nanocatalysts under realistic reaction conditions, and for monitoring the dynamics of catalysis with high spatial, temporal and energy resolution. In this review, we discuss confinement effects in nanocatalysis, a concept that our group has put forward and developed over several years. Taking the confined catalytic systems of carbon nanotubes, metal-confined nano-oxides and 2D layered nanocatalysts as examples, we summarize and analyze the fundamental concepts, the research methods and some of the key scientific issues involved in nanocatalysis. Moreover, we present a perspective on the challenges and opportunities in future research on nanocatalysis from the aspects of: (1) controlled synthesis of nanocatalysts and rational design of catalytically active centers; (2) in situ characterization of nanocatalysts and dynamics of catalytic processes; (3) computational chemistry with a complexity approximating that of experiments; and (4) scale-up and commercialization of nanocatalysts.
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Affiliation(s)
- Fan Yang
- State Key Laboratory of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Dehui Deng
- State Key Laboratory of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xiulian Pan
- State Key Laboratory of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Qiang Fu
- State Key Laboratory of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Xinhe Bao
- State Key Laboratory of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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14
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Yang Y, Zhang P. First-principles molecular dynamics study of water dissociation on the γ-U(1 0 0) surface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:175005. [PMID: 25835568 DOI: 10.1088/0953-8984/27/17/175005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Based on first-principles molecular dynamics simulations at finite temperatures, we systematically study the adsorption and dissociation of water molecules on the γ-U(1 0 0) surface. We predict that water molecules spontaneously dissociate upon approaching the native γ-U(1 0 0) surface. The dissociation results from electronic interactions between surface uranium 6d states and 1b2, 3a1, and 1b1 molecular orbitals of water. With segregated Nb atoms existing on the surface, adsorbing water molecules also dissociate spontaneously because Nb 3d electronic states can also interact with the molecular orbitals similarly. After dissociation, the isolated hydrogen atoms are found to diffuse fast on both the γ-U surface and that with a surface substitutional Nb atom, which is very similar to the 'Hot-Atom' dissociation of oxygen molecules on the Al(1 1 1) surface. From a series of consecutive molecular dynamics simulations, we further reveal that on both the γ-U surface and that with a surface substitutional Nb atom, one surface U atom will be pulled out to form the U-O-U structure after dissociative adsorption of 0.44 ML water molecules. This result indicates that oxide nucleus can form at low coverage of water adsorption on the two surfaces.
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Affiliation(s)
- Yu Yang
- Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088, People's Republic of China
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15
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Song CL, Wang L, He K, Ji SH, Chen X, Ma XC, Xue QK. Probing Dirac fermion dynamics in topological insulator Bi2Se3 films with a scanning tunneling microscope. PHYSICAL REVIEW LETTERS 2015; 114:176602. [PMID: 25978246 DOI: 10.1103/physrevlett.114.176602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Indexed: 06/04/2023]
Abstract
Scanning tunneling microscopy and spectroscopy have been used to investigate the femtosecond dynamics of Dirac fermions in the topological insulator Bi2Se3 ultrathin films. At the two-dimensional limit, bulk electrons become quantized and the quantization can be controlled by the film thickness at a single quintuple layer level. By studying the spatial decay of standing waves (quasiparticle interference patterns) off steps, we measure directly the energy and film thickness dependence of the phase relaxation length lϕ and inelastic scattering lifetime τ of topological surface-state electrons. We find that τ exhibits a remarkable (E - EF)(-2) energy dependence and increases with film thickness. We show that the features revealed are typical for electron-electron scattering between surface and bulk states.
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Affiliation(s)
- Can-Li Song
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Ke He
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Shuai-Hua Ji
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xi Chen
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Xu-Cun Ma
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
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16
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Ming W, Blair S, Liu F. Quantum size effect on dielectric function of ultrathin metal film: a first-principles study of Al(1 1 1). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:505302. [PMID: 25419653 DOI: 10.1088/0953-8984/26/50/505302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using first-principles calculations, we show manifestations of the quantum size effect in the dielectric function ε(2) of free-standing Al(1 1 1) ultrathin films of 1 monolayer to 20 monolayers, taking into account size dependent contributions from both interband and intraband electronic transitions. Overall the in-plane components (interband transition) of ε(2) increase with film thickness at all frequencies, converging towards a constant value. However, the out-of-plane components of ε(2) show a more complex behavior, and, only at frequencies less than 0.75 eV, increase with film thickness without convergence. This suggests that ultrathin films can possibly be used for low-loss plasmonics devices in the visible and ultraviolet range. Our findings may shed light on searching for low-loss plasmonic materials via quantum size effect.
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Affiliation(s)
- Wenmei Ming
- Department of Materials Science and Engineering, University of Utah, 201 Presidents Cir, Salt Lake City, UT 84112, USA
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17
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Bouhassoune M, Zimmermann B, Mavropoulos P, Wortmann D, Dederichs PH, Blügel S, Lounis S. Quantum well states and amplified spin-dependent Friedel oscillations in thin films. Nat Commun 2014; 5:5558. [PMID: 25424343 DOI: 10.1038/ncomms6558] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/14/2014] [Indexed: 11/09/2022] Open
Abstract
Electrons mediate many of the interactions between atoms in a solid. Their propagation in a material determines its thermal, electrical, optical, magnetic and transport properties. Therefore, the constant energy contours characterizing the electrons, in particular the Fermi surface, have a prime impact on the behaviour of materials. If anisotropic, the contours induce strong directional dependence at the nanoscale in the Friedel oscillations surrounding impurities. Here we report on giant anisotropic charge density oscillations focused along specific directions with strong spin-filtering after scattering at an oxygen impurity embedded in the surface of a ferromagnetic thin film of Fe grown on W(001). Utilizing density functional theory, we demonstrate that by changing the thickness of the Fe films, we control quantum well states confined to two dimensions that manifest as multiple flat energy contours, impinging and tuning the strength of the induced charge oscillations which allow to detect the oxygen impurity at large distances (≈50 nm).
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Affiliation(s)
- Mohammed Bouhassoune
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Bernd Zimmermann
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Phivos Mavropoulos
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Daniel Wortmann
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Peter H Dederichs
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Stefan Blügel
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institut &Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, D-52425 Jülich, Germany
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18
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Sharma HR, Smerdon JA, Nugent PJ, Ribeiro A, McLeod I, Dhanak VR, Shimoda M, Tsai AP, McGrath R. Crystalline and quasicrystalline allotropes of Pb formed on the fivefold surface of icosahedral Ag-In-Yb. J Chem Phys 2014; 140:174710. [PMID: 24811658 DOI: 10.1063/1.4873596] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Crystalline and quasicrystalline allotropes of Pb are formed by evaporation on the fivefold surface of the icosahedral (i) Ag-In-Yb quasicrystal under ultra-high vacuum. Lead grows in three dimensional quasicrystalline order and subsequently forms fivefold-twinned islands with the fcc(111) surface orientation atop of the quasicrystalline Pb. The islands exhibit specific heights (magic heights), possibly due to the confinement of electrons in the islands. We also study the adsorption behavior of C60 on the two allotropes of Pb. Scanning tunneling microcopy reveals that a high corrugation of the quasicrystalline Pb limits the diffusion of the C60 molecules and thus produces a disordered film, similar to adsorption behavior of the same molecules on the clean substrate surface. However, the sticking coefficient of C60 molecules atop the Pb islands approaches zero, regardless of the overall C60 coverage.
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Affiliation(s)
- H R Sharma
- Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - J A Smerdon
- Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - P J Nugent
- Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - A Ribeiro
- Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - I McLeod
- Department of Physics and the Stephenson Institute for Renewable Energy, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - V R Dhanak
- Department of Physics and the Stephenson Institute for Renewable Energy, The University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - M Shimoda
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - A P Tsai
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - R McGrath
- Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX, United Kingdom
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19
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Ionescu R, George A, Ruiz I, Favors Z, Mutlu Z, Liu C, Ahmed K, Wu R, Jeong JS, Zavala L, Mkhoyan KA, Ozkan M, Ozkan CS. Oxygen etching of thick MoS2 films. Chem Commun (Camb) 2014; 50:11226-9. [DOI: 10.1039/c4cc03911d] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oxygen annealing of thick MoS2 films results in randomly oriented and controllable triangular etched shapes, forming pits with uniform etching angles.
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Affiliation(s)
- Robert Ionescu
- Department of Chemistry
- University of California
- Riverside, USA
| | - Aaron George
- Materials Science and Engineering Program
- University of California
- Riverside, USA
| | - Isaac Ruiz
- Department of Electrical Engineering
- University of California
- Riverside, USA
| | - Zachary Favors
- Materials Science and Engineering Program
- University of California
- Riverside, USA
| | - Zafer Mutlu
- Materials Science and Engineering Program
- University of California
- Riverside, USA
| | - Chueh Liu
- Materials Science and Engineering Program
- University of California
- Riverside, USA
| | - Kazi Ahmed
- Department of Electrical Engineering
- University of California
- Riverside, USA
| | - Ryan Wu
- Department of Chemical Engineering and Materials Science
- University of Minnesota
- Minneapolis, USA
| | - Jong S. Jeong
- Department of Chemical Engineering and Materials Science
- University of Minnesota
- Minneapolis, USA
| | - Lauro Zavala
- Department of Mechanical Engineering
- University of California
- Riverside, USA
| | - K. Andre Mkhoyan
- Department of Chemical Engineering and Materials Science
- University of Minnesota
- Minneapolis, USA
| | - Mihri Ozkan
- Department of Chemistry
- University of California
- Riverside, USA
- Department of Electrical Engineering
- University of California
| | - Cengiz S. Ozkan
- Materials Science and Engineering Program
- University of California
- Riverside, USA
- Department of Mechanical Engineering
- University of California
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20
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Lin MK, Nakayama Y, Chen CH, Wang CY, Jeng HT, Pi TW, Ishii H, Tang SJ. Tuning gap states at organic-metal interfaces via quantum size effects. Nat Commun 2013; 4:2925. [DOI: 10.1038/ncomms3925] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 11/12/2013] [Indexed: 01/06/2023] Open
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21
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Mao HQ, Li N, Chen X, Xue QK. Mechanical properties of H2Pc self-assembled monolayers at the single molecule level by noncontact atomic force microscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:084004. [PMID: 22310060 DOI: 10.1088/0953-8984/24/8/084004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The mechanical properties of molecular self-assembled monolayers (SAMs) play an important role in understanding the interactions between molecules in the self-assembly, the interactions between molecules and substrate, and thus the formation mechanism of SAMs. Using a high-resolution noncontact atomic force microscope (NC-AFM) combined with a scanning tunneling microscope (STM), we have successfully obtained the sub-molecular resolution of a H(2)Pc self-assembled monolayer grown on a Pb(111) surface. A 2 × 2 superstructure was observed in both AFM and STM topographic images. The lateral critical force of removing a H(2)Pcmolecule from its SAM and moving a single H(2)Pc molecule on Pb(111) were measured. An oscillation of the critical force along the edge of the H(2)Pc SAM with a period of two molecular sites was observed, which can be attributed to the 2 × 2 superstructure. The lateral critical force caused by intermolecular interaction was found to be 25 pN on average and is typically two times larger than the molecule-substrate interaction.
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Affiliation(s)
- Han-Qing Mao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, People's Republic of China
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22
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Zhu W, Chen H, Bevan KH, Zhang Z. Formation of graphene p-n superlattices on Pb quantum wedged islands. ACS NANO 2011; 5:3707-3713. [PMID: 21473606 DOI: 10.1021/nn200052f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
On the basis of first-principles calculations within density functional theory, we report on a novel scheme to create graphene p-n superlattices on Pb wedged islands with quantum stability. Pb(111) wedged islands grown on vicinal Si(111) extend over several Si steps, forming a wedged structure with atomically flat tops. The monolayer thickness variation due to the underlying substrate steps is a sizable fraction of the total thickness of the wedged islands and gives rise to a bilayer oscillation in the work function of Pb(111) due to quantum size effects. Here, we demonstrate that when a graphene sheet is placed on the surface of such a Pb wedged island, the spatial work function oscillation on the Pb wedged island surface caused by the underlying steps results in an oscillatory shift in the graphene Dirac point with respect to the Fermi level. Furthermore, by applying an external electric field of ∼0.5 V/Å in the surface normal direction, the Fermi level of the system can be globally tuned to an appropriate position such that the whole graphene layer becomes a graphene p-n superlattice of seamless junctions, with potentially exotic physical properties and intriguing applications in nanoelectronics.
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Affiliation(s)
- Wenguang Zhu
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, United States.
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23
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Bartels C, Cooper R, Auerbach DJ, Wodtke AM. Energy transfer at metal surfaces: the need to go beyond the electronic friction picture. Chem Sci 2011. [DOI: 10.1039/c1sc00181g] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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24
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Jia Y, Wu B, Li C, Einstein TL, Weitering HH, Zhang Z. Strong quantum size effects in Pb(111) thin films mediated by anomalous Friedel oscillations. PHYSICAL REVIEW LETTERS 2010; 105:066101. [PMID: 20867988 DOI: 10.1103/physrevlett.105.066101] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Indexed: 05/29/2023]
Abstract
Using first-principles calculations within density functional theory, we study Friedel oscillations (FOs) in the electron density at different metal surfaces and their influence on the lattice relaxation and stability of ultrathin metal films. We show that the FOs at the Pb(111) surface decay as 1/x with the distance x from the surface, different from the conventional 1/x(2) power law at other metal surfaces. The underlying physical reason for this striking difference is tied to the strong nesting of the two different Fermi sheets along the Pb(111) direction. The interference of the strong FOs emanating from the two surfaces of a Pb(111) film, in turn, not only results in superoscillatory interlayer relaxations around the center of the film, but also determines its stability in the quantum regime. As a simple and generic picture, the present findings also explain why quantum size effects are exceptionally robust in Pb(111) films.
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Affiliation(s)
- Yu Jia
- School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan, 450052, China
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25
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Quantum size effects on the work function of metallic thin film nanostructures. Proc Natl Acad Sci U S A 2010; 107:12761-5. [PMID: 20615989 DOI: 10.1073/pnas.0915171107] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this paper, we present the direct observation of quantum size effects (QSE) on the work function in ultrathin Pb films. By using scanning tunneling microscopy and spectroscopy, we show that the very existence of quantum well states (QWS) in these ultrathin films profoundly affects the measured tunneling decay constant kappa, resulting in a very rich phenomenon of "quantum oscillations" in kappa as a function of thickness, L, and bias voltage, V(s). More specifically, we find that the phase of the quantum oscillations in kappa vs. L depends sensitively upon the bias voltage, which often results in a total phase reversal at different biases. On the other hand, at very low sample bias (|V(s)| < 0.03 V) the measurement of kappa vs. L accurately reflects the quantum size effect on the work function. In particular, the minima in the quantum oscillations of kappa vs. L occur at the locations where QWS cross the Fermi energy, thus directly unraveling the QSE on the work function in ultrathin films, which was predicted more than three decades ago. This further clarifies several contradictions regarding the relationship between the QWS locations and the work function.
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26
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Xie YP, Wu YZ, Gong XG. Quantum-well states in a double-well system: an example of Cu/Co(Ni)/Cu. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:052203. [PMID: 21386334 DOI: 10.1088/0953-8984/22/5/052203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The quantum-well (QW) states in the Cu/Co double-well system are studied by first-principles calculations. We have shown that the monolayer Ni or Co as a heterogeneous spacer in Cu QW can not only disturb the QW states extending into the whole structure, but also create new QW states because of the interfaces introduced, resulting in sub-well-confining electrons. If the QW state energy in two sub-wells is close to each other, these two sub-well QW states can couple together. We have also demonstrated that monolayer Co and Ni spacers play different roles for modulating QW states at different energy levels, which also result in a complicated distribution of QW states. The obtained results are in good agreement with experiment data.
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Affiliation(s)
- Yao-Ping Xie
- Surface Physics Laboratory and Laboratory for Computational Physical Sciences, Fudan University, Shanghai 200433, People's Republic of China
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27
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28
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Song CL, Wang YL, Ning YX, Jia JF, Chen X, Sun B, Zhang P, Xue QK, Ma X. Tailoring Phthalocyanine Metalation Reaction by Quantum Size Effect. J Am Chem Soc 2010; 132:1456-7. [DOI: 10.1021/ja908040g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Can-Li Song
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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29
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Hu Z, Yang Y, Sun B, Shao X, Wang W, Zhang P. Quantum oscillations in adsorption energetics of atomic oxygen on Pb(111) ultrathin films: A density-functional theory study. J Chem Phys 2010; 132:024703. [DOI: 10.1063/1.3277674] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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30
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Aballe L, Barinov A, Stojić N, Binggeli N, Mentes TO, Locatelli A, Kiskinova M. The electron density decay length effect on surface reactivity. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:015001. [PMID: 21386216 DOI: 10.1088/0953-8984/22/1/015001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The correlation between the thickness-dependent oxidation rate of ultrathin Al films on W(110) and the quantum-well states (QWS) resulting from electron confinement in the Al film has been explored by combined x-ray photoemission electron microscopy (XPEEM), low energy electron microscopy (LEEM), and first-principles calculations. Hybridization with substrate electronic states is observed to alter the film electronic structure, strongly modifying the electron density decay length in vacuum. The decay length, rather than the density of states at the Fermi energy, is found to dominate the observed reactivity trends.
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Affiliation(s)
- L Aballe
- ALBA Synchrotron Light Facility, Carretera BP 1413, Barcelona, Spain
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31
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Zhou H, Qiu C, Liu Z, Yang H, Hu L, Liu J, Yang H, Gu C, Sun L. Thickness-Dependent Morphologies of Gold on N-Layer Graphenes. J Am Chem Soc 2009; 132:944-6. [DOI: 10.1021/ja909228n] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Haiqing Zhou
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Caiyu Qiu
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zheng Liu
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Huaichao Yang
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lijun Hu
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ji Liu
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haifang Yang
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Changzhi Gu
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lianfeng Sun
- National Centre for Nanoscience and Technology, Beijing, 100190, China, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China, and Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
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32
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Affiliation(s)
- Hanno H Weitering
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN 37996, USA.
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33
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Miller T, Chou MY, Chiang TC. Phase relations associated with one-dimensional shell effects in thin metal films. PHYSICAL REVIEW LETTERS 2009; 102:236803. [PMID: 19658957 DOI: 10.1103/physrevlett.102.236803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2009] [Indexed: 05/28/2023]
Abstract
The physical and chemical properties of thin metal films show damped oscillations as a function of film thickness (one-dimensional shell effects). While the oscillation period, determined by subband crossings of the Fermi level, is the same for all properties, the phases can be different. Specifically, oscillations in the work function and surface energy are offset by 1/4 of a period. For Pb(111) films, this offset is approximately 0.18 monolayers, a seemingly very small effect. However, aliasing caused by the discrete atomic layer structure leads to striking out-of-phase beating patterns displayed by these two quantities.
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Affiliation(s)
- T Miller
- Department of Physics, University of Illinois, Urbana, Illinois 61801-3080, USA
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Wang J, Ma XC, Qi Y, Fu YS, Ji SH, Lu L, Xie XC, Jia JF, Chen X, Xue QK. An unusual magnetoresistance effect in the heterojunction structure of an ultrathin single-crystal Pb film on silicon substrate. NANOTECHNOLOGY 2008; 19:475708. [PMID: 21836289 DOI: 10.1088/0957-4484/19/47/475708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Superconductor films on semiconductor substrates have drawn much attention recently since the derived superconductor-based electronics have been shown to be promising for future data processing and storage technologies. By growing atomically uniform single-crystal epitaxial Pb films of several nanometers thick on Si wafers to form a sharp superconductor-semiconductor heterojunction, we have obtained an unusual magnetoresistance effect when the Pb film is superconducting. In addition to the large fundamental interest in this effect, the simple structure, and compatibility and scalability with current Si-based semiconductor technology offer a great opportunity for integrating superconducting circuits and detectors in a single chip.
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Affiliation(s)
- Jian Wang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100080, People's Republic of China. The Center for Nanoscale Science and Department of Physics, Pennsylvania State University, University Park, PA 16802-6300, USA
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Chen X, Fu YS, Ji SH, Zhang T, Cheng P, Ma XC, Zou XL, Duan WH, Jia JF, Xue QK. Probing superexchange interaction in molecular magnets by spin-flip spectroscopy and microscopy. PHYSICAL REVIEW LETTERS 2008; 101:197208. [PMID: 19113306 DOI: 10.1103/physrevlett.101.197208] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Indexed: 05/11/2023]
Abstract
The superexchange mechanism in cobalt phthalocyanine (CoPc) thin films was studied by a low temperature scanning tunneling microscope. The CoPc molecules were found to form one-dimensional antiferromagnetic chains in the film. Collective spin excitations in individual molecular chains were measured with spin-flip associated inelastic electron tunneling spectroscopy. By spatially mapping the spin-flipping channels with submolecular precision, we are able to explicitly identify the specific molecular orbitals that mediate the superexchange interaction between molecules.
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Affiliation(s)
- Xi Chen
- Department of Physics, Tsinghua University, Beijing 100084, China
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Zhang Z, Zhang Y, Fu Q, Zhang H, Yao Y, Ma T, Tan D, Xue Q, Bao X. Modulation of surface reactivity via electron confinement in metal quantum well films: O2 adsorption on Pb∕Si(111). J Chem Phys 2008; 129:014704. [DOI: 10.1063/1.2919992] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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37
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Jiang P, Ma X, Ning Y, Song C, Chen X, Jia JF, Xue QK. Quantum Size Effect Directed Selective Self-Assembling of Cobalt Phthalocyanine on Pb(111) Thin Films. J Am Chem Soc 2008; 130:7790-1. [DOI: 10.1021/ja801255w] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Peng Jiang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xucun Ma
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yanxiao Ning
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Canli Song
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xi Chen
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jin-Feng Jia
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qi-Kun Xue
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China, and Department of Physics, Tsinghua University, Beijing 100084, China
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Yao YX, Liu X, Fu Q, Li WX, Tan DL, Bao XH. Unique Reactivity of Confined Metal Atoms on a Silicon Substrate. Chemphyschem 2008; 9:975-9. [DOI: 10.1002/cphc.200700840] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Yang Y, Zhou G, Wu J, Duan W, Xue QK, Gu BL, Jiang P, Ma X, Zhang SB. The adsorption of O2 on Pb films and the effect of quantum modulation: A first-principles prediction. J Chem Phys 2008; 128:164705. [DOI: 10.1063/1.2905210] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Fu YS, Ji SH, Chen X, Ma XC, Wu R, Wang CC, Duan WH, Qiu XH, Sun B, Zhang P, Jia JF, Xue QK. Manipulating the Kondo resonance through quantum size effects. PHYSICAL REVIEW LETTERS 2007; 99:256601. [PMID: 18233541 DOI: 10.1103/physrevlett.99.256601] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Indexed: 05/25/2023]
Abstract
Manipulating the Kondo effect by quantum confinement has been achieved by placing magnetic molecules on silicon-supported nanostructures. The Kondo resonance of individual manganese phthalocyanine (MnPc) molecules adsorbed on the top of Pb islands was studied by scanning tunneling spectroscopy. Oscillating Kondo temperatures as a function of film thickness were observed and attributed to the formation of the thickness-dependent quantum-well states in the host Pb islands. The present approach provides a technologically feasible way for single spin manipulation by precise thickness control of thin films.
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Affiliation(s)
- Ying-Shuang Fu
- Department of Physics, Tsinghua University, Beijing 100084, China
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