Energy Spectra and Oscillatory Magnetization of Two-Electron Self-Assembled InGaAs/GaAs Ring-Like Nanostructures

We have analyzed the effect of the Coulomb interaction on the energy spectrum and the magnetization of two electrons in a strained In$_x$Ga$_{1-x}$As/GaAs ring-like nanostructure with realistic parameters inferred from our X-STM data. With increasing magnetic field, the lowest spin-singlet and spin- triplet states sequentially replace each other as the ground state. This is reminiscent of the Aharonov-Bohm effect for the ring-like structures. The exchange interaction leads to a more complicated oscillatory structure of the magnetic moment of the two electrons as a function of the magnetic field as compared to the magnetization pattern for a single-electron ring-like nanostructure. We discuss the relevance of the two-electron systems for the interpretation of the Aharonov-Bohm oscillations in the persistent current observed in low temperature magnetization measurements on self-assembled In$_x$Ga$_{1-x}$As/GaAs ring-like nanostructures.