We review recent studies by optics methods of emergent phases in the quantum Hall (QH) regimes of double layers with finite tunneling at Landau level filling factor nu=1. In measurements of spin excitations by inelastic light scattering and of elastically scattered Rayleigh light under the application of in-plane magnetic fields, we uncovered evidence of a quantum phase transition that occurs when a many-body tunneling gap collapses. The transformation can be regarded as a transition from an incompressible highly correlated QH state to a compressible composite-fermion bilayer system. The correlated QH state is characterized by the presence of populations of bound electron-hole pairs across the tunneling gap. Quantitative determinations of the density of such excitonic pairs are obtained from inelastic light scattering spectra of spin excitations. The correlated QH state displays resonant Rayleigh scattering with unusual temperature dependence.
Seeing emergent phases in quantum Hall double layers
Pellegrini V;Luin S;
2007
Abstract
We review recent studies by optics methods of emergent phases in the quantum Hall (QH) regimes of double layers with finite tunneling at Landau level filling factor nu=1. In measurements of spin excitations by inelastic light scattering and of elastically scattered Rayleigh light under the application of in-plane magnetic fields, we uncovered evidence of a quantum phase transition that occurs when a many-body tunneling gap collapses. The transformation can be regarded as a transition from an incompressible highly correlated QH state to a compressible composite-fermion bilayer system. The correlated QH state is characterized by the presence of populations of bound electron-hole pairs across the tunneling gap. Quantitative determinations of the density of such excitonic pairs are obtained from inelastic light scattering spectra of spin excitations. The correlated QH state displays resonant Rayleigh scattering with unusual temperature dependence.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
