Mesoscopic Fano effect in a spin splitter with a side-coupled quantum dot

Date
2012
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Source Title
Physics Letters A
Print ISSN
0375-9601
Electronic ISSN
1873-2429
Publisher
Elsevier B.V.
Volume
376
Issue
10-11
Pages
1078 - 1083
Language
English
Type
Article
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Abstract

We investigate the interplay between the spin interference and the Fano effect in a three-lead mesoscopic ring with a side-coupled quantum dot (QD). A uniform Rashba spin-orbit coupling and a perpendicular magnetic field are tuned such that the ring operates as a spin splitter in the absence of the QD: one lead is used to inject unpolarized electrons and the remaining (output) leads collect almost polarized spin currents. By applying a gate potential to the quantum dot a pair of spin-split levels sweeps the bias window and leads to Fano interference. The steady-state spin and charge currents in the leads are calculated for a finite bias applied across the ring via the non-equilibrium Green's function formalism. When the QD levels participate to transport we find that the spin currents exhibit peaks and dips whereas the charge currents present Fano lineshapes. The location of the side-coupled quantum dot and the spin splitting of its levels also affect the interference and the output currents. The opposite response of output currents to the variation of the gate potential allows one to use this system as a single parameter current switch. We also analyze the dependence of the splitter efficiency on the spin splitting on the QD.

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Keywords
Fano effect, Mesoscopic rings, Rashba spin-orbit coupling
Citation
Published Version (Please cite this version)