Kondo Effect and SpinCharge Separation in Quantum Dots
Abstract
The Kondo effect in a quantum dot is discussed. In the standard Coulomb blockade setting, tunneling between the dot and the leads is weak, the number of electrons in the dot is welldefined and discrete; the Kondo effect may be considered in the framework of the conventional onelevel Anderson impurity model. It turns out however, that the Kondo temperature T_{K} in the case of weak tunneling is extremely low. In the opposite case of almost reflectionless singlemode junctions connecting the dot to the leads, the average charge of the dot is not discrete. Surprisingly, its spin may remain quantized: s=1/2 or s=0, depending (periodically) on the gate voltage. Such a "spincharge separation" occurs because, unlike an Anderson impurity, a quantum dot carries a broadband, dense spectrum of discrete levels. In the doublet state, the Kondo effect develops with a significantly enhanced T_{K}. Like in the weaktunneling regime, the enhanced T_{K} exhibits strong mesoscopic fluctuations. The statistics of the fluctuations is universal, and related to the PorterThomas statistics of the wave function fluctuations.
 Publication:

International Journal of Modern Physics B
 Pub Date:
 2001
 DOI:
 10.1142/S0217979201005921
 Bibcode:
 2001IJMPB..15.1426G