title: Microwave spectroscopy of the low-filling-factor bilayer electron solid in a wide quantum well.
abstract: At the low Landau filling factor termination of the fractional quantum Hall effect series, two-dimensional electron systems exhibit an insulating phase that is understood as a form of pinned Wigner solid. Here we use microwave spectroscopy to probe the transition to the insulator for a wide quantum well sample that can support single-layer or bilayer states depending on its overall carrier density. We find that the insulator exhibits a resonance which is characteristic of a bilayer solid. The resonance also reveals a pair of transitions within the solid, which are not accessible to dc transport measurements. As density is biased deeper into the bilayer solid regime, the resonance grows in specific intensity, and the transitions within the insulator disappear. These behaviours are suggestive of a picture of the insulating phase as an emulsion of liquid and solid components.
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA.
authors.forename: A T
authors.initials: AT
authors.lastname: Hatke
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.affiliation: National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA.
authors.forename: L W
authors.initials: LW
authors.lastname: Engel
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: M
authors.initials: M
authors.lastname: Shayegan
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: West
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Baldwin