title: Strongly correlated two-dimensional plasma explored from entropy measurements.
abstract: Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute two-dimensional electron systems at elevated and low temperatures, respectively. Probing their thermodynamics represents challenge because of lack of an adequate technique. Here, we report a thermodynamic method to measure the entropy per electron in gated structures. Our technique appears to be three orders of magnitude superior in sensitivity to a.c. calorimetry, allowing entropy measurements with only 10(8) electrons. This enables us to investigate the correlated plasma regime, previously inaccessible experimentally in two-dimensional electron systems in semiconductors. In experiments with clean two-dimensional electron system in silicon-based structures, we traced entropy evolution from the plasma to Fermi liquid regime by varying electron density. We reveal that the correlated plasma regime can be mapped onto the ordinary non-degenerate Fermi gas with an interaction-enhanced temperature-dependent effective mass. Our method opens up new horizons in studies of low-dimensional electron systems.
authors.affiliation: 1] Lebedev Physical Institute of the RAS, Moscow 119991, Russia [2] Moscow Institute of Physics and Technology, Moscow 141700, Russia.
authors.forename: A Y
authors.initials: AY
authors.lastname: Kuntsevich
authors.affiliation: Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Y V
authors.initials: YV
authors.lastname: Tupikov
authors.affiliation: 1] Lebedev Physical Institute of the RAS, Moscow 119991, Russia [2] Moscow Institute of Physics and Technology, Moscow 141700, Russia.
authors.forename: V M
authors.initials: VM
authors.lastname: Pudalov
authors.affiliation: 1] Moscow Institute of Physics and Technology, Moscow 141700, Russia [2] L.D. Landau Institute for Theoretical Physics, Kosygina Street 2, Moscow 119334, Russia.
authors.forename: I S
authors.initials: IS
authors.lastname: Burmistrov