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Title: Time-dependent quantum transport and power-law decay of the transient current in a nano-relay and nano-oscillator
Authors: Cuansing, E.C. 
Liang, G. 
Issue Date: 15-Oct-2011
Citation: Cuansing, E.C., Liang, G. (2011-10-15). Time-dependent quantum transport and power-law decay of the transient current in a nano-relay and nano-oscillator. Journal of Applied Physics 110 (8) : -. ScholarBank@NUS Repository.
Abstract: Time-dependent nonequilibrium Green's functions are used to study electron transport properties in a device consisting of two linear chain leads and a time-dependent interlead coupling that is switched on non-adiabatically. We derive a numerically exact expression for the particle current and examine its characteristics as it evolves in time from the transient regime to the long-time steady-state regime. We find that just after switch-on, the current initially overshoots the expected long-time steady-state value, oscillates and decays as a power law, and eventually settles to a steady-state value consistent with the value calculated using the Landauer formula. The power-law parameters depend on the values of the applied bias voltage, the strength of the couplings, and the speed of the switch-on. In particular, the oscillating transient current decays away longer for lower bias voltages. Furthermore, the power-law decay nature of the current suggests an equivalent series resistor-inductor-capacitor circuit wherein all of the components have time-dependent properties. Such dynamical resistive, inductive, and capacitive influences are generic in nano-circuits where dynamical switches are incorporated. We also examine the characteristics of the dynamical current in a nano-oscillator modeled by introducing a sinusoidally modulated interlead coupling between the two leads. We find that the current does not strictly follow the sinusoidal form of the coupling. In particular, the maximum current does not occur during times when the leads are exactly aligned. Instead, the times when the maximum current occurs depend on the values of the bias potential, nearest-neighbor coupling, and the interlead coupling. © 2011 American Institute of Physics.
Source Title: Journal of Applied Physics
ISSN: 00218979
DOI: 10.1063/1.3651390
Appears in Collections:Staff Publications

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