Department of Physics
Condensed Matter Seminar

Coupled electron bilayers in quantum Hall states offer an intriguing possibility to study quantum phases driven by competing terms of the electron-electron interactions. In this talk I will focus on the integer quantum Hall regime at total filling factor 1. I will present measurements of spin excitations by inelastic light scattering at mK temperatures that indicate that an excitonic incompressible phase occurs at large inter-layer correlation while a compressible Fermi-metal phase of composite fermions (loosely, electrons with two magnetic flux quanta attached) prevails as the inter-layer interaction is reduced. I will also present both inelastic and elastic light scattering data that shed light on the nature of the incompressible-compressible quantum phase transition that occurs as the inter-layer coupling is finely reduced by application of an in-plane magnetic field.