title: SU(4) Fermi liquid state and spin filtering in a double quantum dot system.
abstract: 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 pi/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.
authors.affiliation: Sektion Physik and Center for Nanoscience, LMU München, Theresienstrasse 37, 80333 München, Germany.
authors.forename: László
authors.initials: L
authors.lastname: Borda
authors.forename: Gergely
authors.initials: G
authors.lastname: Zaránd
authors.forename: Walter
authors.initials: W
authors.lastname: Hofstetter
authors.forename: B I
authors.initials: BI
authors.lastname: Halperin
authors.forename: Jan
authors.initials: J
authors.lastname: von Delft