Quantum dot in high magnetic fields: Correlated tunneling of electrons probes the spin configuration at the edge of the dot

Quantum dot systems with a large number of electrons $\left(\approx 50\right)$ defined in a two-dimensional electron system (2DES) show a striking regularity in the occurrence of split Kondo peaks in the differential conductance as a function of the electron number and the magnetic field applied perpendicularly to the plane of the 2DES. The observations are consistent with the well-known redistribution of electrons from the core to the edge of the quantum dot with increasing magnetic field leading to a sequence of paired and unpaired spin configurations at the edge of the quantum dot. The results demonstrate the importance of the tunnel coupling of different electronic states to the leads for the observation of the Kondo effect.