Titled, Passage from Spin-Polarized Surface States to Unpolarized Quantum Well States in Topologically Nontrivial Sb Films, the article appeared as the cover article in the July 15, 2011 issue of Physical Review Letters. See the abstract below as well as a link to the table of contents of the issue.
Topological materials have unusual surface spin properties including a net surface spin current protected by the bulk symmetry properties. When such materials are reduced to thin films, their gapless spin-polarized surface states must connect, by analytic continuation, to bulk-derived quantum-well states, which are spin-unpolarized in centrosymmetric systems. The nature of this passage in a model system, Sb films, is investigated. Angle-resolved photoemission shows a smooth transition, while calculations elucidate the correlated evolution of the spin and charge distributions in real space.