|Schematic image of the structure of the Weyl semimetal in momentum space. |
Two diabolical points are shown in red, within the bulk three-dimensional Brillouin zone.
"Topology, the mathematical description of the robustness of form, appears throughout physics, and provides strong constraints on many physical systems. It has long been known that it plays a key role in understanding the exotic phenomena of the quantum Hall effect. Recently, it has been found to generate robust and interesting bulk and surface phenomena in “ordinary” band insulators described by the old Bloch theory of solids."