Evidence of Soft-Mode Quantum Phase Transitions in Electron Double Layers
Vittorio Pellegrini,
Aron Pinczuk,
Brian
S. Dennis,
Annette S. Plaut,
Loren N. Pfeiffer,
Ken W. West
Inelastic light scattering by low-energy spin-excitations reveals
three distinct configurations of spin of electron double layers in
gallium arsenide quantum wells at even-integer quantum Hall states. The
transformations among these spin states appear as quantum phase
transitions driven by the interplay between Coulomb interactions and
Zeeman splittings. One of the transformations correlates with the
emergence of a spin-flip intersubband excitation at vanishingly low
energy and provides direct evidence of a link between quantum phase
transitions and soft collective excitations in a two-dimensional
electron system.
V. Pellegrini, Bell Laboratories, Lucent Technologies, Murray
Hill, NJ 07974, USA, and Scuola Normale Superiore and Istituto
Nazionale per la Fisica della Materia, Pisa, Italy. A. Pinczuk, Bell
Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA, and
Departments of Physics and Applied Physics, Columbia University, New
York, NY 10027, USA. B. S. Dennis, L. N. Pfeiffer, K. W. West, Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974, USA. A. S. Plaut, Department of Physics, University of Exeter,
Exeter EX4 4QL, UK.
