Changes in the Magnetization of a Double Quantum Dot

From accurate measurements of the energy states in a double quantum dot, we deduce the change in magnetization due to single electron tunneling. We observe crossings and anticrossings in the energy spectrum as a function of magnetic field. The change in magnetization exhibits wiggles as a function of magnetic field with maximum values of a few effective Bohr magnetons in GaAs. These wiggles are a measure of the chaotic motion of the discrete energy states versus magnetic field. Our results show good agreement with a numeric calculation but deviate significantly from semiclassical estimates.