Abstract
Direct measurements of the compressibility K of the 2D electron gas at both zero magnetic field B and in the high-field extreme quantum limit, ν<1, are reported. A new method is used to determine both the magnitude and IsignR of K. At B=0 we find changes sign and becomes negative as the 2D density is reduced. At high B, exhibits negative anomalies near both ν=0 and 1. Compressibility features near the fractional fillings ν=1/3 and 2/3 give thermodynamic evidence for dilute interacting quasiparticle gases.
- Received 26 September 1991
DOI:https://doi.org/10.1103/PhysRevLett.68.674
©1992 American Physical Society