Activation study of the bilayer image quantum Hall state

We investigated the bilayer fractional quantum Hall state (FQHS) at total Landau level filling factor View the MathML source, which is interpreted as the bilayer ν=1 integer quantum Hall state (IQHS) of composite fermions. We carried out detailed magnetotransport experiments of the bilayer View the MathML source FQHS in tilted magnetic field. The data are compared with reported data of the bilayer ν=1 IQHS. We found that the commensurate - incommensurate phase transition, which occurs in the bilayer ν=1 IQHS, is missing in the bilayer View the MathML source FQHS.