Ground-state emission from a single InAs/GaAs self-assembled quantum dot structure in ultrahigh magnetic fields

We report on the magnetic field dispersion of the exciton spin-splitting and diamagnetic shift in single InAs/GaAs quantum dots up to B=28 T. We have found substantial differences between field evolution of the emission from tall (4 nm height) and flat (2 nm height) dots. Strongly nonlinear spin-splitting is observed in the former case, while in the latter case the nonlinearity is much weaker. The diamagnetic shift of the ground-state emission can be explained in terms of geometric size of the dots. While it can be approximated by a quadratic field dependence in dots of large confining potential, a substantial linear contribution must be included to account for the diamagnetic shift in dots of weaker confinement.