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Pramanik A, Kang HS. Electronic and magnetic properties of metal-(4,4'-bipyridine) sandwich complexes and their nanowires. J Phys Chem A 2011; 115:219-24. [PMID: 21155551 DOI: 10.1021/jp110442x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using calculations based on density functional theory, we have investigated the geometric, energetic, and magnetic properties of complexes of 4,4'-bipyridine (BPY) with metal atoms M (= Li, V, and Ti). The systems of interest include BPY-M(2) and BPY(2)-M(2) complexes and (BPY-M(2))(x) nanowires in which the sandwich structure is stacked infinitely along one direction. For each of these systems, a detailed analysis was performed on the electronic structure. First, we found that BPY-M (M = V and Ti) binding is stronger than BPY-Li binding because of the covalent nature of the former interaction. The difference in the magnetic properties of BPY-M(2) and BPY(2)-M(2) (M = V and Ti) complexes can be understood in terms of the different strengths of the M-M interactions mediated by d(M) or sd(M)-hybridized orbitals. Second, we found that the (BPY-Li(2))(x) nanowire is a semiconductor, whereas (BPY-V(2))(x) and (BPY-Ti(2))(x) nanowires are magnetic metals due to the spin-polarization in d(z)2(M)-derived bands.
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Affiliation(s)
- Anup Pramanik
- Institute of Engineering Research and Department of Nano and Advanced Materials, College of Engineering, Jeonju University, Hyoja-dong, Wansan-ku, Chonju, Chonbuk 560-759, Republic of Korea
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52
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53
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Zhu L, Zhang T, Yi M, Wang J. Ab Initio Study on Mixed Inorganic/Organic Ligand Sandwich Clusters: BzTMC60, TM = Sc−Co. J Phys Chem A 2010; 114:9398-403. [DOI: 10.1021/jp106129r] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Liyan Zhu
- Department of Physics, Southeast University, Nanjing, 211189, People’s Republic of China
| | - Tingting Zhang
- Department of Physics, Southeast University, Nanjing, 211189, People’s Republic of China
| | - Mengxi Yi
- Department of Physics, Southeast University, Nanjing, 211189, People’s Republic of China
| | - Jinlan Wang
- Department of Physics, Southeast University, Nanjing, 211189, People’s Republic of China
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54
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Zhang Z, Wu X, Guo W, Zeng XC. Carrier-Tunable Magnetic Ordering in Vanadium−Naphthalene Sandwich Nanowires. J Am Chem Soc 2010; 132:10215-7. [DOI: 10.1021/ja1029057] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Zhuhua Zhang
- Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China, Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, and Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Xiaojun Wu
- Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China, Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, and Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Wanlin Guo
- Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China, Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, and Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, China
| | - Xiao Cheng Zeng
- Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China, Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, and Department of Materials of Science and Engineering, University of Science and Technology of China, Hefei 230026, China
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55
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Yi Z, Shen X, Sun L, Shen Z, Hou S, Sanvito S. Tuning the magneto-transport properties of nickel-cyclopentadienyl multidecker clusters by molecule-electrode coupling manipulation. ACS NANO 2010; 4:2274-2282. [PMID: 20232857 DOI: 10.1021/nn901784t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Spin transport in a series of organometallic multidecker clusters made of alternating nickel atoms and cyclopentadienyl (Cp) rings is investigated by using first-principles quantum transport simulations. The magnetic moment of finite NinCp(n+1) clusters in the gas phase is a periodic function of the number of NiCp monomers, n, regardless of the cluster termination and despite the fact that the band structure of the infinite [NiCp]infinity chain is nonmagnetic. In contrast, when the clusters are sandwiched between gold electrodes, their spin polarization is found to strongly depend on the molecule-electrode coupling. On the one hand, a substantial magnetic moment and a large spin polarization can be detected for NiCp2 and Ni4Cp5 with both weak and modest molecule-electrode coupling. On the other hand, when the coupling of the clusters is strong and mediated by Ni adatoms, the spin polarization of all NinCp(n+1) (n = 1-4) clusters is destroyed, although their low-bias conductance is large. This demonstrates that the magnetism and the spin-transport properties of fragile molecular magnets, such as NinCp(n+1), can be tuned in a controllable way by changing the contact geometry.
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Affiliation(s)
- Zelong Yi
- Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871, People's Republic of China
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56
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Martínez JI, García-Lastra JM, López MJ, Alonso JA. Optical to ultraviolet spectra of sandwiches of benzene and transition metal atoms: Time dependent density functional theory and many-body calculations. J Chem Phys 2010; 132:044314. [DOI: 10.1063/1.3300129] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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57
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Ab Initio Study of Bond Characteristics and Magnetic Properties of Mixed-Sandwich VnBzmCpk Clusters. J Phys Chem A 2010; 114:2319-23. [DOI: 10.1021/jp907834v] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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58
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Shen L, Jin H, Ligatchev V, Yang SW, Sullivan MB, Feng Y. Oxidization states of metal atoms in linear bimetallic multi-sandwich molecules Vn(FeCp2)(n+1) and magnetic moment enhancement mechanism of its 1D wire. Phys Chem Chem Phys 2010; 12:4555-9. [DOI: 10.1039/b927272k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Lei Shen
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
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59
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Zhang X, Ng MF, Wang Y, Wang J, Yang SW. Theoretical studies on structural, magnetic, and spintronic characteristics of sandwiched Eu(n)COT(n+1) (n = 1-4) clusters. ACS NANO 2009; 3:2515-2522. [PMID: 19685860 DOI: 10.1021/nn900401b] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Europium (Eu)-cyclootetatrene (COT = C(8)H(8)) multidecker clusters (Eu(n)COT(n+1), n = 1-4) are studied by relativistic density functional theory calculations. These clusters are found to be thermodynamically stable with freely rotatable COT rings, and their total magnetic moments (MMs) increase linearly along with the number of Eu atoms. Each Eu atom contributes about 7 mu(B) to the cluster. Meanwhile, the internal COT rings have little MM contribution while the external COT rings have about 1 mu(B) MM aligned in opposite direction to that of the Eu atoms. The total MM of the Eu(n)COT(n+1) clusters can thus be generalized as 7n - 2 mu(B) where n is the number of Eu atoms. Besides, the ground states of these clusters are ferromagnetic and energetically competitive with the antiferromagnetic states, meaning that their spin states are very unstable, especially for larger clusters. More importantly, we uncover an interesting bonding characteristic of these clusters in which the interior ionic structure is capped by two hybrid covalent-ionic terminals. We suggest that such a characteristic makes the Eu(n)COT(n+1) clusters extremely stable. Finally, we reveal that for the positively charged clusters, the hybrid covalent-ionic terminals will tip further toward the interior part of the clusters to form deeper covalent-ionic caps. In contrast, the negatively charged clusters turn to pure ionic structures.
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Affiliation(s)
- Xiuyun Zhang
- Department of Physics, Southeast University, Nanjing 211189, PR China
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60
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Affiliation(s)
- Xiaojun Wu
- Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588
| | - Xiao Cheng Zeng
- Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588
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61
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Zhang X, Wang J, Zeng XC. Ab Initio Study of Structural, Electronic, and Magnetic Properties of Vn(C60)m Complexes. J Phys Chem A 2009; 113:5406-13. [DOI: 10.1021/jp8064272] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiuyun Zhang
- Department of Physics, Southeast University, Nanjing 211189, P. R. China, and Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588
| | - Jinlan Wang
- Department of Physics, Southeast University, Nanjing 211189, P. R. China, and Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588
| | - Xiao Cheng Zeng
- Department of Physics, Southeast University, Nanjing 211189, P. R. China, and Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588
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62
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Zhang X, Wang J, Gao Y, Zeng XC. Ab initio study of structural and magnetic properties of TM(n)(ferrocene)(n+1) (TM = Sc, Ti, V, Mn) sandwich clusters and nanowires (n = infinity). ACS NANO 2009; 3:537-545. [PMID: 19256546 DOI: 10.1021/nn800794c] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Structural and magnetic properties of multidecker sandwich clusters TM(n)(ferrocene)(n+1) [TM = V, Ti, Sc, Mn, ferrocene=FeCp(2), n = 1-3] and corresponding one-dimensional sandwich nanowires (n = infinity) are studied by means of gradient-corrected density functional theory. The TM(n)(FeCp(2))(n+1) clusters are highly stable polyferrocene-like sandwich structures due to strong Fe-Cp interaction. The total magnetic moment of TM(n)(FeCp(2))(n+1) (TM = V, Ti, Mn) increases linearly with the size n. More strikingly, Ti(n)(FeCp(2))(n+1) and V(n)(FeCp(2))(n+1) (n = 1-3) exhibit high magnetic moments 4, 8, 12 mu(B) and 1, 6, 11 mu(B), respectively. In contrast, Sc(n)(FeCp(2))(n+1) clusters are paramagnetic. The [TM(FeCp(2))](infinity) sandwich nanowires are ferromagnetic semiconductors whose band gap is 0.361, 0.506, 0.51, and 1.310 eV, respectively, for TM = Ti, Sc, V, and Mn. Among the four sandwich nanowires, [V(FeCp(2))](infinity) nanowire possesses the highest magnetic moment (5 mu(B)) per unit cell.
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Affiliation(s)
- Xiuyun Zhang
- Department of Physics, Southeast University, Nanjing, 211189, PR China
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63
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Xu K, Huang J, Lei S, Su H, Boey FYC, Li Q, Yang J. Efficient organometallic spin filter based on Europium-cyclooctatetraene wire. J Chem Phys 2009. [DOI: 10.1063/1.3224175] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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64
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Wang L, Cai Z, Wang J, Lu J, Luo G, Lai L, Zhou J, Qin R, Gao Z, Yu D, Li G, Mei WN, Sanvito S. Novel one-dimensional organometallic half metals: vanadium-cyclopentadienyl, vanadium-cyclopentadienyl-benzene, and vanadium-anthracene wires. NANO LETTERS 2008; 8:3640-3644. [PMID: 18816146 DOI: 10.1021/nl8016016] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
By using the density functional theory, we find that organometallic multidecker sandwich clusters V(2 n+1)Cp(2 n+2), Vn(FeCp2)(n+1) (Cp=cyclopentadienyl), and V(2n)Ant(n+1) (Ant=anthracene) may have linear structures, and their total magnetic moments generally increase with the cluster size. The one-dimensional (VCp)infinity, (VBzVCp)infinity (Bz=benzene), and (V2Ant)infinity wires are predicted to be ferromagnetic half-metals, while the one-dimensional (VCpFeCp)infinity wire is a ferromagnetic semiconductor. The spin transportation calculations show that the finite V2(n+1)Cp2(n+2) and Vn(FeCp2)(n+1) sandwich clusters coupled to gold electrodes are nearly perfect spin-filters.
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Affiliation(s)
- Lu Wang
- State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, Peoples Republic of China
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65
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Shen L, Yang SW, Ng MF, Ligatchev V, Zhou L, Feng Y. Charge-Transfer-Based Mechanism for Half-Metallicity and Ferromagnetism in One-Dimensional Organometallic Sandwich Molecular Wires. J Am Chem Soc 2008; 130:13956-60. [DOI: 10.1021/ja804053a] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lei Shen
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
| | - Shuo-Wang Yang
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
| | - Man-Fai Ng
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
| | - Valeri Ligatchev
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
| | - Liping Zhou
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
| | - Yuanping Feng
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore, Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore, and Jiangsu Key Laboratory of Thin Films, Department of Physics, Suzhou University, Suzhou, 215006, China
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66
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Wang J, Zhu L, Zhang X, Yang M. Size- and Shape-Dependent Polarizabilities of Sandwich and Rice-Ball ConBzm Clusters from Density Functional Theory. J Phys Chem A 2008; 112:8226-30. [PMID: 18700735 DOI: 10.1021/jp803204z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Jinlan Wang
- Department of Physics, Southeast University, Nanjing 211189, China, and Institute for Nanobiomedical Technology, State Key Laboratory of Biotherapy, West-China Medical School/West-China Hospital, Sichuan University, Chengdu 610041, China
| | - Liyan Zhu
- Department of Physics, Southeast University, Nanjing 211189, China, and Institute for Nanobiomedical Technology, State Key Laboratory of Biotherapy, West-China Medical School/West-China Hospital, Sichuan University, Chengdu 610041, China
| | - Xiuyun Zhang
- Department of Physics, Southeast University, Nanjing 211189, China, and Institute for Nanobiomedical Technology, State Key Laboratory of Biotherapy, West-China Medical School/West-China Hospital, Sichuan University, Chengdu 610041, China
| | - Mingli Yang
- Department of Physics, Southeast University, Nanjing 211189, China, and Institute for Nanobiomedical Technology, State Key Laboratory of Biotherapy, West-China Medical School/West-China Hospital, Sichuan University, Chengdu 610041, China
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67
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Wang J, Zhang X, Schleyer PVR, Chen Z. Density functional theory studies of inorganic metallocene multidecker Vn(P6)n+1 (n=1–4) sandwich clusters. J Chem Phys 2008; 128:104706. [DOI: 10.1063/1.2883971] [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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68
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Zhou L, Yang SW, Ng MF, Sullivan MB, Tan, Shen L. One-Dimensional Iron−Cyclopentadienyl Sandwich Molecular Wire with Half Metallic, Negative Differential Resistance and High-Spin Filter Efficiency Properties. J Am Chem Soc 2008; 130:4023-7. [DOI: 10.1021/ja7100246] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Liping Zhou
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Shuo-Wang Yang
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Man-Fai Ng
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Michael B. Sullivan
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Tan
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Lei Shen
- Institute of High Performance Computing, 1 Science Park Road, #01-01 The Capricorn, Singapore 117528, Singapore, Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore, and Department of Physics, National University of Singapore, Singapore 117542, Singapore
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69
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Theoretical study on the spin states and intra-cluster spin relaxation of the one-dimensional metal–benzene sandwich clusters: M2(C6H6)3 (M=Sc, Ti, V). Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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70
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Kim WY, Choi YC, Kim KS. Understanding structures and electronic/spintronic properties of single molecules, nanowires, nanotubes, and nanoribbons towards the design of nanodevices. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b804359k] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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71
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Zhang X, Wang J. Structural, Electronic, and Magnetic Properties of Con(benzene)m Complexes. J Phys Chem A 2007; 112:296-304. [DOI: 10.1021/jp076647o] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiuyun Zhang
- Department of Physics, Southeast University, Nanjing 211189, P. R. China
| | - Jinlan Wang
- Department of Physics, Southeast University, Nanjing 211189, P. R. China
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72
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Mokrousov Y, Atodiresei N, Bihlmayer G, Heinze S, Blügel S. The interplay of structure and spin-orbit strength in the magnetism of metal-benzene sandwiches: from single molecules to infinite wires. NANOTECHNOLOGY 2007; 18:495402. [PMID: 20442471 DOI: 10.1088/0957-4484/18/49/495402] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Based on first-principles density functional theory calculations, we explore the electronic and magnetic properties of experimentally producible sandwiches and infinite wires made of repeating benzene molecules and transition-metal atoms of V, Nb, and Ta. We describe the bonding mechanism in the molecules and in particular concentrate on the origin of magnetism in these structures. We find that all the considered systems have sizable magnetic moments and ferromagnetic spin ordering, with the single exception of the V(3)Bz(4) molecule. By including the spin-orbit coupling into our calculations we determine the easy and hard axes of the magnetic moment, the strength of the uniaxial magnetic anisotropy energy (MAE), relevant for the thermal stability of magnetic orientation, and the change of the electronic structure with respect to the direction of the magnetic moment, important for spin-transport properties. While for the V-based compounds the values of the MAE are only of the order of 0.05-0.5 meV per metal atom, increasing the spin-orbit strength by substituting V with heavier Nb and Ta allows one to achieve an increase in anisotropy values by one to two orders of magnitude. The rigid stability of magnetism in these compounds together with the strong ferromagnetic ordering makes them attractive candidates for spin-polarized transport applications. For a Nb-benzene infinite wire the occurrence of ballistic anisotropic magnetoresistance is demonstrated.
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Affiliation(s)
- Y Mokrousov
- Institute for Applied Physics, University of Hamburg, Jungiusstrasse 9a, 20355 Hamburg, Germany.
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73
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Sohnlein BR, Lei Y, Yang DS. Electronic states of neutral and cationic bis(benzene) titanium and vanadium sandwich complexes studied by pulsed field ionization electron spectroscopy. J Chem Phys 2007; 127:114302. [PMID: 17887832 DOI: 10.1063/1.2771158] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Ti- and V-bz2 (bz=C6H6) sandwich complexes have been prepared in a laser-ablation cluster beam source and studied by pulsed field ionization-zero electron kinetic energy photoelectron spectroscopy and theoretical calculations. The ground electronic states of the neutral Ti- and V-bz2 complexes are determined to be 1A1g and 2A1g, and their ionization energies are measured to be 5.732+/-0.001 and 5.784+/-0.002 eV, respectively. These neutral complexes have eta6 binding and are in an eclipsed D6h configuration with flat benzene rings. Ionization of the 1A1g and 2A1g neutral states of Ti- and V-bz2 yields the 2B1g and 3B1g ion states, respectively, in a D2h point group with slightly puckered benzene rings. In addition, the binding and structures of these two complexes are compared with other first-row transition metal bis(benzene) sandwiches.
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Affiliation(s)
- Bradford R Sohnlein
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
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74
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Miyajima K, Yabushita S, Knickelbein MB, Nakajima A. Stern−Gerlach Experiments of One-Dimensional Metal−Benzene Sandwich Clusters: Mn(C6H6)m (M = Al, Sc, Ti, and V). J Am Chem Soc 2007; 129:8473-80. [PMID: 17579402 DOI: 10.1021/ja070137q] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A molecular beam of multilayer metal-benzene organometallic clusters Mn(C6H6)m (M = Al, Sc, Ti, and V) was produced by a laser vaporization synthesis method, and their magnetic deflections were measured. Multidecker sandwich clusters of transition-metal atoms and benzene Scn(C6H6)n+1 (n = 1, 2) and Vn(C6H6)n+1 (n = 1-4) possess magnetic moments that increase monotonously with n. The magnetic moments of Al(C6H6), Scn(C6H6)n+1, and Vn(C6H6)n+1 are smaller than that of their spin-only values as a result of intracluster spin relaxation, an effect that depends on the orbital angular momenta and bonding characters of the orbitals containing electron spin. While Ti(C6H6)2 was found to be nonmagnetic, Tin(C6H6)n+1 (n = 2, 3) possess nonzero magnetic moments. The mechanism of ferromagnetic spin ordering in M2(C6H6)3 (M = Sc, Ti, V) is discussed qualitatively in terms of molecular orbital analysis. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition-metal atoms are formally zerovalent.
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Affiliation(s)
- Ken Miyajima
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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75
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Koleini M, Paulsson M, Brandbyge M. Efficient organometallic spin filter between single-wall carbon nanotube or graphene electrodes. PHYSICAL REVIEW LETTERS 2007; 98:197202. [PMID: 17677656 DOI: 10.1103/physrevlett.98.197202] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Indexed: 05/16/2023]
Abstract
We present a theoretical study of spin transport in a class of molecular systems consisting of an organometallic benzene-vanadium cluster placed in between graphene or single-wall carbon-nanotube-model contacts. Ab initio modeling is performed by combining spin density functional theory and nonequilibrium Green's function techniques. We consider weak and strong cluster-contact bonds. Depending on the bonding we find from 73% (strong bonds) up to 99% (weak bonds) spin polarization of the electron transmission, and enhanced polarization with increased cluster length.
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Affiliation(s)
- Mohammad Koleini
- Department of Micro- and Nanotechnology (MIC), NanoDTU, Technical University of Denmark (DTU), Ørsteds Plads, Bldg. 345E, DK-2800 Lyngby, Denmark
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76
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Yang LM, Ding YH, Sun CC. Assembly and Stabilization of a Planar Tetracoordinated Carbon Radical CAl3Si: A Way To Design Spin-Based Molecular Materials. J Am Chem Soc 2007; 129:1900-1. [PMID: 17256941 DOI: 10.1021/ja068334x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Li-Ming Yang
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China
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77
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Nagaoka S, Matsumoto T, Ikemoto K, Mitsui M, Nakajima A. Soft-Landing Isolation of Multidecker V2(benzene)3 Complexes in an Organic Monolayer Matrix: An Infrared Spectroscopy and Thermal Desorption Study. J Am Chem Soc 2007; 129:1528-9. [PMID: 17283996 DOI: 10.1021/ja068442j] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Shuhei Nagaoka
- Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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78
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Maslyuk VV, Bagrets A, Meded V, Arnold A, Evers F, Brandbyge M, Bredow T, Mertig I. Organometallic benzene-vanadium wire: A one-dimensional half-metallic ferromagnet. PHYSICAL REVIEW LETTERS 2006; 97:097201. [PMID: 17026394 DOI: 10.1103/physrevlett.97.097201] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Indexed: 05/12/2023]
Abstract
Using density functional theory we perform theoretical investigations of the electronic properties of a freestanding one-dimensional organometallic vanadium-benzene wire. This system represents the limiting case of multidecker Vn(C6H6)(n+1) clusters which can be synthesized with established methods. We predict that the ground state of the wire is a 100% spin-polarized ferromagnet (half-metal). Its density of states is metallic at the Fermi energy for the minority electrons and shows a semiconductor gap for the majority electrons. We find that the half-metallic behavior is conserved up to 12% longitudinal elongation of the wire. Ab initio electron transport calculations reveal that finite size vanadium-benzene clusters coupled to ferromagnetic Ni or Co electrodes will work as nearly perfect spin filters.
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Affiliation(s)
- Volodymyr V Maslyuk
- Martin-Luther-Universität Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany
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79
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Reininghaus F, Korb T, Schoeller H. Fingerprints of the magnetic polaron in nonequilibrium electron transport through a quantum wire coupled to a ferromagnetic spin chain. PHYSICAL REVIEW LETTERS 2006; 97:026803. [PMID: 16907473 DOI: 10.1103/physrevlett.97.026803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Indexed: 05/11/2023]
Abstract
We study nonequilibrium quantum transport through a mesoscopic wire coupled via local exchange to a ferromagnetic spin chain. Using the Keldysh formalism in the self-consistent Born approximation, we identify fingerprints of the magnetic polaron state formed by hybridization of electronic and magnon states. Because of its low decoherence rate, we find coherent transport signals. Both elastic and inelastic peaks of the differential conductance are discussed as a function of external magnetic fields, the polarization of the leads, and the electronic level spacing of the wire.
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Affiliation(s)
- Frank Reininghaus
- Institut für Theoretische Physik A, RWTH Aachen, 52056 Aachen, Germany
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80
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Li SD, Miao CQ, Ren GM, Guo JC. Triple-Decker Transition-Metal Complexes (CnHn)M(B6C)M(CnHn) (M = Fe, Ru, Mn, Re;n = 5, 6) Containing Planar Hexacoordinate Carbon Atoms. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600118] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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81
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Zhou J, Wang WN, Fan KN. Novel compounds with cobalt, copper, and nickel dimers sandwiched between benzene molecules: A DFT study. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.04.113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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82
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Mitsui M, Nagaoka S, Matsumoto T, Nakajima A. Soft-Landing Isolation of Vanadium−Benzene Sandwich Clusters on a Room-Temperature Substrate Using n-Alkanethiolate Self-Assembled Monolayer Matrixes. J Phys Chem B 2006; 110:2968-71. [PMID: 16494294 DOI: 10.1021/jp057194v] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gas-phase synthesized vanadium-benzene 1:2 (VBz(2)) sandwich clusters were size-selectively deposited onto bare gold and long-chain n-alkanethiolate [-S-(CH(2))(n-1)-CH(3); n = 16, 18, and 22] self-assembled monolayer (SAM)-coated gold substrates under ultrahigh vacuum (UHV) conditions. Investigation of the resulting deposited clusters was performed by infrared reflection absorption spectroscopy (IRAS) and thermal desorption spectroscopy (TDS). The IR frequencies of the soft-landed VBz(2) clusters show excellent agreement with the fundamentals reported in IR data of VBz(2) in an argon matrix. The analysis of IRAS spectra reveals that while there was no orientational preference of the VBz(2) clusters on a bare gold substrate, the VBz(2) clusters deposited onto the SAM substrates were highly oriented with the molecular axis 70-80 degrees tilted off the surface normal. In addition, analysis of TDS spectra revealed unusually large adsorption heats of the physisorbed VBz(2) clusters. The present results are explained by cluster penetration into the long-chain alkanethiolate SAM and for the first time demonstrate the matrix isolation of gas-phase organometallic clusters around room temperature.
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83
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Xiang H, Yang J, Hou JG, Zhu Q. One-Dimensional Transition Metal−Benzene Sandwich Polymers: Possible Ideal Conductors for Spin Transport. J Am Chem Soc 2006; 128:2310-4. [PMID: 16478186 DOI: 10.1021/ja054751i] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the electronic and magnetic properties of the proposed one-dimensional transition metal (TM = Sc, Ti, V, Cr, and Mn) -benzene (Bz) sandwich polymers by means of density functional calculations. [V(Bz)](infinity) is found to be a quasi-half-metallic ferromagnet, and half-metallic ferromagnetism is predicted for [Mn(Bz)](infinity). Moreover, we show that stretching the [TM(Bz)](infinity) polymers could have dramatic effects on their electronic and magnetic properties. The elongated [V(Bz)](infinity) displays half-metallic behavior, and [Mn(Bz)](infinity) stretched to a certain degree becomes an antiferromagnetic insulator. The possibilities to stabilize the ferromagnetic order in [V(Bz)](infinity) and [Mn(Bz)](infinity) polymers at finite temperatures are discussed. We suggest that the hexagonal bundles composed by these polymers might display intrachain ferromagnetic order at finite temperatures by introducing interchain exchange coupling.
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Affiliation(s)
- Hongjun Xiang
- Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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84
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Wang J, Jellinek J. Infrared Spectra of VnBzn+1 Sandwich Clusters: A Theoretical Study of Size Evolution. J Phys Chem A 2005; 109:10180-2. [PMID: 16833309 DOI: 10.1021/jp055532m] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Results of density functional theory computations of infrared (IR) spectra of linear sandwich V(n)Bz(n+1), n = 1-6, complexes are presented. It is shown that the systematic changes in the spectra as a function of the complex size can be categorized and understood in terms of responses of the "parent" modes of the Bz molecule and the VBz complex. The analysis presented should be applicable to a broad class of linear sandwich systems.
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85
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Kang HS. Magnetic Couplings in Vanadium Aromatic Sandwich Complexes and Their Crystals by Using DFT Methods. J Phys Chem A 2005; 109:9292-8. [PMID: 16833271 DOI: 10.1021/jp0524577] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using density functional theory, we have theoretically studied the origin of ferromagnetic coupling of spins in the long multiple deckers of vanadium sandwich complexes with benzene (Bz). This is done by calculating the band structure of their infinite one-dimensional (1D) crystals along the periodic (=Z) direction. We find that the magnetic coupling can be ascribed to spin polarization in the band (= those derived from d(z2)) whose k states are not involved in the formation of partial covalent bonds between vanadium atoms and benzene rings. We have also studied magnetic and electronic properties of multiple deckers of a naphthalene (Np)-vanadium complex. We find that there is a stronger covalent interaction as well as a stronger electrostatic interaction between V and Np rings than between V and Bz rings. This suggests that there is a possibility of longer multiple deckers of a Np-V complex. In addition, ferrimagnetic coupling of spins is expected, resulting in a magnetic moment 45% larger than that of the Bz-V complex at the same length. For their 1D crystals, band structure analysis also shows that the origin of magnetic coupling in long multiple deckers should be similar to that of Bz-V multiple deckers.
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Affiliation(s)
- Hong Seok Kang
- College of Liberal Arts, Jeonju University, Hyoja-dong, Wansan-ku, Chonju, Chonbuk 560-759, Republic of Korea.
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