Observation of a magnetically induced Wigner solid

E. Y. Andrei, G. Deville, D. C. Glattli, and F. I. B. Williams

Service de Physique du Solide et de Résonance Magnétique, Institut de Recherche Fondamentale, Commisariat à l'Energie Atomique—Centre d'Etudes Nucléaires de Saclay, 91191 Gif-sur-Yvette Cedex, France

E. Paris and B. Etienne

Laboratoire de Microstructures et de Microélectronique, Centre National de la Recherche Scientifique, 92220 Bagneux, France

The existence of the magnetic-field—induced liquid-to-solid phase transition in an extreme quantum-limit 2D electron plasma is established for electrons at a high-quality GaAs/GaAlAs heterojunction by detection of a gapless magnetophonon excitation branch with radio-frequency spectroscopy. The phase diagram, determined for Wigner-Seitz to Bohr radius ratio 1.6<r_s<2.5, extrapolates to a zero-temperature critical Landau-level filling factor nu _c=0.23±0.04 and a zero—filling-factor melting temperature close to the classical (r_s--> [infinity] ) limit.