Magnetism near the percolation transition in two-dimensional electron systems: effects of interaction and disorder

Bilal Tanatar

Bilkent University

Recent thermodynamic measurements on two-dimensional (2D) electron systems have found diverging behavior in the inverse compressibility, magnetic susceptibility and appearance of ferromagnetism with decreasing electron density. The critical densities for these phenomena coincide with the metal-insulator transition (MIT) recorded in transport measurements. Based on density functional calculations within the local spin-density approximation, we have investigated the compressibility and magnetic susceptibility of a 2D electron gas in the presence of remote impurities. A correlation between the minimum in the inverse compressibility ($\partial\mu /\partial n$) and the maximum of magnetization and magnetic susceptibility was found. This is coincident with the percolation transition point. Based on values we obtain for the inverse participation ratio, this seems to be aslo the MIT point.