Jürg Osterwalder: Topological insulators – new physics with old materials

Materials like Bi-Sb alloys, Bi2Se3 or Bi2Te3 have been known and
studied for decades, mostly for their interesting thermoelectrical
properties. They are insulators with relatively small band gaps,
which are opened by the spin-orbit interaction. Recently, it was
recognized that the topology of the electronic states separated by
this gap is non-trivial. Jürg Osterwalder gives an introduction to
the new aspects of these materials.