Magnetization of multi-component two-dimensional quantum-Hall systems

We present a torque-magnetometry study of bilayer two-dimensional electron gases with different inter-layer barrier widths. At filling factors where a symmetric–anti-symmetric transition takes place we clearly observe steps in magnetization, even though this transition is purely electronic in nature and no direct change of spin or orbital angular momentum is involved. Additionally, in both samples, the apparent size of the magnetization steps associated to the Landau-level transitions is reduced by approximately a factor of two compared to the value typical for a single two-dimensional electron system.