MAGNETIZATION AND INCOMPRESSIBILITY OF A HIGH-MOBILITY 2D ELECTRON-GAS IN THE IQHE

We have measured the magnetization of a single layer, high mobility 2D electron gas in the quantum limit. Sharp diamagnetic jumps in the mag netization are observed when an integer number of Landau levels is fil led. We relate these jumps to incompressibility gaps in the energy spe ctrum of the order of the cyclotron energy, in which a small fraction of the total number of states is present. The spin-splitting of the La ndau levels is observed as well, in particular at v = 1, and gives a m easure of the enhancement of the g-factor. (C) 1998 Elsevier Science B .V. All rights reserved.