First-principles calculation of transport property in nano-devices under an external magnetic field |
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Authors: | Chen Jing-Zhe Zhang Jin and Han Ru-Shan |
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Institution: | School of Physics, Peking University, Beijing
100871, China |
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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. |
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Keywords: | first-principles quantum
interference phenomenon (QIP) universal conductance fluctuation
(UFC) |
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