中国物理B ›› 2008, Vol. 17 ›› Issue (6): 2208-2215.doi: 10.1088/1674-1056/17/6/045

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

First-principles calculation of transport property in nano-devices under an external magnetic field

陈竞哲, 张进, 韩汝珊   

  1. School of Physics, Peking University, Beijing 100871, China
  • 收稿日期:2007-10-08 修回日期:2007-11-29 出版日期:2008-06-20 发布日期:2008-06-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 90207009, 90206048 and 90406014).

First-principles calculation of transport property in nano-devices under an external magnetic field

Chen Jing-Zhe(陈竞哲), Zhang Jin(张进), and Han Ru-Shan(韩汝珊)   

  1. School of Physics, Peking University, Beijing 100871, China
  • Received:2007-10-08 Revised:2007-11-29 Online:2008-06-20 Published:2008-06-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 90207009, 90206048 and 90406014).

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摘要： The mesoscopic quantum interference phenomenon (QIP) can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green's function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP: universal conductance fluctuation (UCF) and Aharonov--Bohm effect (A--B effect). We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states (DOSs). We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A--B effect is observed and the origin of the oscillation is also discussed.

Abstract: The mesoscopic quantum interference phenomenon (QIP) can be observed and behaves as the oscillation of conductance in nano-devices when the external magnetic field changes. Excluding the factor of impurities or defects, specific QIP is determined by the sample geometry. We have improved a first-principles method based on the matrix Green's function and the density functional theory to simulate the transport behaviour of such systems under a magnetic field. We have studied two kinds of QIP: universal conductance fluctuation (UCF) and Aharonov--Bohm effect (A--B effect). We find that the amplitude of UCF is much smaller than the previous theoretical prediction. We have discussed the origin of difference and concluded that due to the failure of ergodic hypothesis, the ensemble statistics is not applicable, and the conductance fluctuation is determined by the flux-dependent density of states (DOSs). We have also studied the relation between the UCF and the structure of sample. For a specific structure, an atomic circle, the A--B effect is observed and the origin of the oscillation is also discussed.

Key words: first-principles, quantum interference phenomenon (QIP), universal conductance fluctuation (UFC)

中图分类号:  (Nanoelectronic devices)

  • 85.35.-p
71.15.Mb (Density functional theory, local density approximation, gradient and other corrections) 72.10.-d (Theory of electronic transport; scattering mechanisms) 73.23.-b (Electronic transport in mesoscopic systems)