Magnetization of a strongly interacting two-dimensional electron system   in perpendicular magnetic fields
  We measure the thermodynamic magnetization of a low-disordered, strongly correlated two-dimensional electron system in silicon in perpendicular magnetic fields. A new, parameter-free method is used to directly determine the spectrum characteristics (Lande g-factor and the cyclotron mass) when the Fermi level lies outside the spectral gaps and the inter-level interactions between quasiparticles are avoided. Intra-level interactions are found to strongly modify the magnetization, without affecting the determined g* and m*. 
S. Anissimova, A. Venkatesan, A. A. Shashkin, M. R. Sakr, S. V.   Kravchenko, and T. M. Klapwijk