We explore the characteristics of 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 (nu = 1, 3 and 1/3) tunneling occurs at two distinct rates that differ by up to 2 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.
@article{arxiv.cond-mat/9905371,
title = {Tunneling into Ferromagnetic Quantum Hall States: Observation of a Spin Bottleneck},
author = {H. B. Chan and R. C. Ashoori and L. N. Pfeiffer and K. W. West},
journal= {arXiv preprint arXiv:cond-mat/9905371},
year = {2009}
}