de Haas van Alphen oscillations in hybridization-gap insulators as a sudden change in the diamagnetic moment of Landau levels

This note revisits the semi-classical theory of quantum oscillations in hybridization-gap insulators, and shows that the physical origin of the oscillations, at $T=0$ K, is a sudden change in the diamagnetic moment of each Landau level as it crosses the hybridized region of the valence band.