title: Tilt-induced anisotropic to isotropic phase transition at ν = 5/2.
abstract: A modest in-plane magnetic field B(∥) is sufficient to destroy the fractional quantized Hall states at ν = 5/2 and 7/2 and replace them with anisotropic compressible phases. Remarkably, we find that at larger B(∥) these anisotropic phases can themselves be replaced by isotropic compressible phases reminiscent of the composite fermion fluid at ν = 1/2. We present strong evidence that this transition is a consequence of the mixing of Landau levels from different electric subbands. We also report surprising dependences of the energy gaps at ν = 5/2 and 7/3 on the width of the confinement potential.
authors.affiliation: California Institute of Technology, Pasadena, 91125, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Xia
authors.forename: Vaclav
authors.initials: V
authors.lastname: Cvicek
authors.forename: J P
authors.initials: JP
authors.lastname: Eisenstein
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.forename: K W
authors.initials: KW
authors.lastname: West