Magnetization of a two-dimensional electron gas with a second filled subband

We have measured the magnetization of a dual-subband two-dimensional electron gas, confined in a GaAs/ AlGaAs heterojunction. In contrast to two-dimensional electron gases with a single subband, we observe non-1/B-periodic, triangularly shaped oscillations of the magnetization with an amplitude significantly less than 1μ* B per electron. All three effects are explained by a field-dependent self-consistent model, demonstrating that the shape of the magnetization is dominated by oscillations in the confining potential. Additionally, at 1 K, we observe small oscillations at magnetic fields where Landau levels of the two different subbands cross.