Nonlinear orbital magnetic response in isolated quantum dots

The magnetic response of an ensemble of quantum dots all having the same macroscopic parameters but different defect configurations is calculated. The number of electrons in each dot is constant. The response is paramagnetic, can be large at small fields for two-dimensional (2D) dots, and has a characteristic nonlinear behavior including a regime where the magnetization is field independent in 2D, albeit with significant corrections. These results are due to the crossover in the spectral correlations brought about by the time-reversal symmetry breaking due to the magnetic field.