“Topological band insulators (TBI’s) are bulk insulators characterized by symmetry protected topological order. A while ago this was subject of an intense theoretical research effort in Leiden executed by Vladimir Juricic, Andrei Mesaros and especially Robert-Jan Slager who earned the exceptional cum laude honor for his thesis work. Presently this research is on stand-by waiting for experimental developments.
The result with the highest impact is the paper introducing the classification of TBI on basis of the space groups  Turn this into direct link to the papers themselves. This is generally regarded as the seminal paper introducing the basic notion while in the mean-time a large literature has emerged further refining this classification method. However, a central theme of our research was all along in the identification of the “bulk defects” associated with the topological order, playing a central role in our classification scheme. Although promising spectacular physics, these have been until recently completely ignored by the large community working on TBI’s, it seems for no other reason than that these require some out of the box thinking.
Dislocations are the work role. These take the role of magnetic flux in the quantum Hall effects. In the subclass of “translationally active” TBI’s electronic zero-modes bind to the dislocations [185, 193] and we showed early on that these are the literal incarnations of the Jackiw-Rossi zero modes: the 2 dimensional incarnations of the famous Su-Schrieffer-Heeger solitons representing the birth place of “electronic” topology. Among others, the resulting “spinon” and “holon” excitations exhibit a mutual Chern-Simons braiding statistics.
This becomes to full flourish in the three dimensional translationally active TBI’s. The zero modes spread in helical 1D modes propagating on the dislocation lines. These are similar as the edge modes in 2D in the sense that the electrons are “unstoppable”. Pending the details of the topological order it may well happen that the electronic conductance on these “perfect wires” becomes completely insensitive to the form and even motion of the dislocation lines . A particular interesting case is realized on grain boundaries: these can be seen as arrays of dislocation lines and the 2D metal “topological metal” formed on the grain boundaries have most peculiar properties .