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

L. Borda·G. Zarand·W. Hofstetter·B. I. Halperin·J. von Delft
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Abstract

We study a symmetrical double quantum dot (DD) system with strong capacitive inter-dot 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 magneto-conductance 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.

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L. Borda, G. Zarand, W. Hofstetter, B. I. Halperin, J. von Delft. 2003-02-06. SU(4) Fermi Liquid State and Spin Filtering in a Double Quantum Dot System. https://doi.org/10.1103/physrevlett.90.026602

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