title: Direct measurements of fractional quantum Hall effect gaps.
abstract: We measure the chemical potential jump across the fractional gap in the low-temperature limit in the two-dimensional electron system of GaAs/AlGaAs single heterojunctions. In the fully spin-polarized regime, the gap for filling factor nu=1/3 increases linearly with the magnetic field and is coincident with that for nu=2/3, reflecting the electron-hole symmetry in the spin-split Landau level. In low magnetic fields, at the ground-state spin transition for nu=2/3, a correlated behavior of the nu=1/3 and nu=2/3 gaps is observed.
authors.affiliation: Institute of Solid State Physics, Chernogolovka, Moscow District, Russia.
authors.forename: V S
authors.initials: VS
authors.lastname: Khrapai
authors.forename: A A
authors.initials: AA
authors.lastname: Shashkin
authors.forename: M G
authors.initials: MG
authors.lastname: Trokina
authors.forename: V T
authors.initials: VT
authors.lastname: Dolgopolov
authors.forename: V
authors.initials: V
authors.lastname: Pellegrini
authors.forename: F
authors.initials: F
authors.lastname: Beltram
authors.forename: G
authors.initials: G
authors.lastname: Biasiol
authors.forename: L
authors.initials: L
authors.lastname: Sorba
mesh_terms: D003080:Cold Temperature; D004583:Electrons; D060526:Magnetic Fields; D011789:Quantum Theory