中国物理B ›› 2010, Vol. 19 ›› Issue (5): 57206-057206.doi: 10.1088/1674-1056/19/5/057206

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Size effect of quantum conductance in carbon nanotube Y-Junctions

刘红   

  1. Physics Department, Nanjing Normal University, Nanjing 210046, China
  • 收稿日期:2009-07-16 修回日期:2009-10-10 出版日期:2010-05-15 发布日期:2010-05-15
  • 基金资助:
    Project supported by the Natural Science Foundation of Jiangsu Education Department (Grant No.~04KJB140065) in China.

Size effect of quantum conductance in carbon nanotube Y-Junctions

Liu Hong(刘红)   

  1. Physics Department, Nanjing Normal University, Nanjing 210046, China
  • Received:2009-07-16 Revised:2009-10-10 Online:2010-05-15 Published:2010-05-15
  • Supported by:
    Project supported by the Natural Science Foundation of Jiangsu Education Department (Grant No.~04KJB140065) in China.

摘要: This paper studies the quantum conductance properties of three-terminated carbon nanotube Y-junctions, which are built by connecting three (5,5) single-walled carbon nanotubes. The results show that the quantum conductance at the Fermi energy oscillates periodically with the junction's size, and the number of oscillating periodic layers is 3 which is the same as that in the two terminated $(10,0)/m(5,5)/(10,0)$ junctions. Moreover, this Y-junction with different size exhibits obvious different distribution of electron current in the two drain branches, called shunt valve effect of electronic current. Thus the degree of this effect can be controlled and modulated directly by constructing the three branches' sizes or the distribution of defect. The results show in detail that the difference between the two drain currents can be up to two times for some constructions with special sizes. In addition, the uniform distribution of defects in the Y-junction leads to lower quantum conductance than that of other defect configurations.

Abstract: This paper studies the quantum conductance properties of three-terminated carbon nanotube Y-junctions, which are built by connecting three (5,5) single-walled carbon nanotubes. The results show that the quantum conductance at the Fermi energy oscillates periodically with the junction's size, and the number of oscillating periodic layers is 3 which is the same as that in the two terminated $(10,0)/m(5,5)/(10,0)$ junctions. Moreover, this Y-junction with different size exhibits obvious different distribution of electron current in the two drain branches, called shunt valve effect of electronic current. Thus the degree of this effect can be controlled and modulated directly by constructing the three branches' sizes or the distribution of defect. The results show in detail that the difference between the two drain currents can be up to two times for some constructions with special sizes. In addition, the uniform distribution of defects in the Y-junction leads to lower quantum conductance than that of other defect configurations.

Key words: single-walled carbon nanotube, Y-junction, quantum conductance, local density of state

中图分类号:  (Nanotubes)

  • 73.63.Fg
73.22.-f (Electronic structure of nanoscale materials and related systems) 71.15.Ap (Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.))