Evidence for a Collective Ground State in Si Inversion Layers in the Extreme Quantum Limit

Abstract

Infrared measurements of the cyclotron resonance in the two-dimensional electron gas reveal a remarkable line narrowing and shift if and only if the lowest Landau level is partially occupied. This behavior cannot be explained in terms of single-electron models, and strongly suggests a highly correlated or crystallized ground state, whose properties are compared with existing theories.