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Title: Nonequilibrium Keldysh formalism for interacting leads-Application to quantum dot transport driven by spin bias
Authors: Li, Y.
Jalil, M.B.A. 
Tan, S.G. 
Keywords: Differential conductance
Kondo effect
Spin transport
Issue Date: Jun-2012
Citation: Li, Y., Jalil, M.B.A., Tan, S.G. (2012-06). Nonequilibrium Keldysh formalism for interacting leads-Application to quantum dot transport driven by spin bias. Annals of Physics 327 (6) : 1484-1493. ScholarBank@NUS Repository.
Abstract: The conductance through a mesoscopic system of interacting electrons coupled to two adjacent leads is conventionally derived via the Keldysh nonequilibrium Green's function technique, in the limit of noninteracting leads [Y.Meir, N.S.Wingreen, Phys. Rev. Lett. 68 (1992) 2512]. We extend the standard formalism to cater for a quantum dot system with Coulombic interactions between the quantum dot and the leads. The general current expression is obtained by considering the equation of motion of the time-ordered Green's function of the system. The nonequilibrium effects of the interacting leads are then incorporated by determining the contour-ordered Green's function over the Keldysh loop and applying Langreth's theorem. The dot-lead interactions significantly increase the height of the Kondo peaks in density of states of the quantum dot. This translates into two Kondo peaks in the spin differential conductance when the magnitude of the spin bias equals that of the Zeeman splitting. There also exists a plateau in the charge differential conductance due to the combined effect of spin bias and the Zeeman splitting. The low-bias conductance plateau with sharp edges is also a characteristic of the Kondo effect. The conductance plateau disappears for the case of asymmetric dot-lead interaction. © 2012 Elsevier Inc.
Source Title: Annals of Physics
ISSN: 00034916
DOI: 10.1016/j.aop.2012.01.003
Appears in Collections:Staff Publications

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