Observation of a spin bottleneck for tunneling into the nu=1 quantum Hall state

We measure equilibrium tunneling of electrons from a 3D electrode into a high-mobility 2D electron system. For most 2D Landau level-filling factors, we find that tunneling can be characterized by a single, well-defined tunneling rate. However, for spin-polarized quantum Hall states (v = 1, 3 and 1/3) tunneling occurs at two distinct rates that differ by up to two orders of magnitude. The dependence of the two rates on temperature and tunnel barrier thickness suggests that slow in-plane spin relaxation creates a bottleneck for tunneling of electrons. (C) 2000 Published by Elsevier Science B.V. All rights reserved.