Ph. Cahuzac, M. de Frutos, J Ph. Roux, and K. Bowen in Physics and chemistry offinite systems: from clusters to crystals, P. Jena, S.N. Khanna, and B.K. Rao (eds.) Publishers, Dordrecht,)

PhD thesis, Universiteit Leiden, The Netherlands

in Mesoscopic Electron Transport, L.L. Sohn, L.P. Kouwenhoven, and G. Schon (eds.) Publishers, Dordrecht,)

Ph. Cahuzac, K Hansen, and J. Pedersen

to be published, . 9 KONDO TUNNELING THROUGH A BIASED DOUBLE QUANTUM DOT YSHAI AVISHAI and KONSTANTIN KIKOIN Ilse Katz Center for Nanotechnology, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel Abstract Electron tunneling through a system formed by two coupled quantum dots in a parallel geometry is considered within a generalized Anderson model. The dots are assumed to have nearly equal radii but different (and tunable) gate voltages. In the absence of tunneling to and from the leads, the isolated two-dot system (with two electrons in it) resembles an hydrogen molecule within the Reitler London approximation. In particular, it has a singlet ground state and low lying excited triplet state. When tunneling is switched on, and when the gate voltages are properly tuned the ground state becomes a triplet and singlet and triplet states are intermixed. In the region where charge fluctuations are suppressed, the pertinent antiferromagnectic exchange interaction has the form (JTS + J5TP) -s. It is written in terms of the electron spin s, the double dot spin 1 operator S and an additional vector operator P. The operators S and P generate the algebra o4 of a spin rotator. The related Kondo effect is similar to that of a vertical quantum dot, discussed and analyzed recently. 1 Introduction Experimental discovery of resonance Kondo tunneling through quantum dots under strong Coulomb blockade1 is an impressive recent result in the physics ofnanostructures. The obser­ vation ofKondo-like zero bias anomaly in the tunneling current through planar GaAs/GaAlAs quantum dot (QD) with odd electron occupation and a net spin S = 1/2 confirmed earlier theoretical predictions 2. A natural question then arose whether the Kondo tunneling is