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Phys. Rev. Lett. 90, 026602 (2003) [4 pages]

SU(4) Fermi Liquid State and Spin Filtering in a Double Quantum Dot System

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László Borda1,3, Gergely Zaránd2,3, Walter Hofstetter2, B. I. Halperin2, and Jan von Delft1
1Sektion Physik and Center for Nanoscience, LMU München, Theresienstrasse 37, 80333 München, Germany
2Lyman Physics Laboratory, Harvard University, Cambridge, Massachusetts
3Research Group of the Hungarian Academy of Sciences, Institute of Physics, TU Budapest, H-1521, Hungary

Received 28 June 2002; published 17 January 2003

We study a symmetrical double quantum dot (DD) system with strong capacitive interdot coupling using renormalization group methods. The dots are attached to separate leads, and there can be a weak tunneling between them. In the regime where there is a single electron on the DD the low-energy behavior is characterized by an SU(4)-symmetric Fermi liquid theory with entangled spin and charge Kondo correlations and a phase shift π/4. Application of an external magnetic field gives rise to a large magnetoconductance and a crossover to a purely charge Kondo state in the charge sector with SU(2) symmetry. In a four-lead setup we find perfectly spin-polarized transmission.

© 2003 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.90.026602
DOI:
10.1103/PhysRevLett.90.026602
PACS:
72.15.Qm, 71.27.+a, 75.20.Hr
 
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