title: Thermodynamic density of states of two-dimensional GaAs systems near the apparent metal-insulator transition.
abstract: We perform combined resistivity and compressibility studies of two-dimensional hole and electron systems which show the apparent metal-insulator transition--a crossover in the sign of deltaR/deltaT with changing density. No thermodynamic anomalies have been detected in the crossover region. Instead, despite a tenfold difference in r(s), the compressibility of both electrons and holes is well described by the theory of nonlinear screening of the random potential. We show that the resistivity exhibits a scaling behavior near the percolation threshold found from analysis of the compressibility. Notably, the percolation transition occurs at a much lower density than the crossover.
authors.affiliation: School of Physics, University of Exeter, Exeter EX4 4QL, United Kingdom.
authors.forename: G
authors.initials: G
authors.lastname: Allison
authors.forename: E A
authors.initials: EA
authors.lastname: Galaktionov
authors.forename: A K
authors.initials: AK
authors.lastname: Savchenko
authors.forename: S S
authors.initials: SS
authors.lastname: Safonov
authors.forename: M M
authors.initials: MM
authors.lastname: Fogler
authors.forename: M Y
authors.initials: MY
authors.lastname: Simmons
authors.forename: D A
authors.initials: DA
authors.lastname: Ritchie