In topological materials, electrons can display behavior that is fundamentally differentfrom that in ‘conventional’ matter, and the magnitude of many such ‘exotic’ phenomena is directly proportional to an entity known as the Chern number. New experiments establish for the first time that the theoretically predicted maximum Chern number can be reached—and controlled—in a real material.
Source:
https://phys.org/news/2020-07-cherned-maximum.html