Spin degree of freedom in the ν=1 bilayer electron system investigated by nuclear spin relaxation -: art. no. 096802

The nuclear-spin-relaxation rate 1/T-1 has been measured in a bilayer electron system at and around total Landau level filling factor nu=1. The measured 1/T-1, which probes electron spin fluctuations, is found to increase gradually from the quantum Hall (QH) state at low fields through a phase transition to the compressible state at high fields. Furthermore, 1/T-1 in the QH state shows a noticeable increase away from nu=1. These results demonstrate that, as opposed to common assumption, the electron spin degree of freedom is not completely frozen either in the QH or the compressible states.