In papers studying or searching for topological order (intrinsic or symmetry-protected) in various condensed matter systems (e.g. Field-tuned and zero-field fractional Chern insulators in magic angle graphene), a common refrain of motivation goes as follows:
- Topological physics began with the experimental discovery of the integer and fractional quantum Hall effect, for very clean two-dimensional electron gases in a large magnetic field.
- The large magnetic field is unfortunate, and it would be nice to get rid of it.
- In fact the large field is not necessary, and equally interesting physics can arise in our system due to strong interactions, time-reversal breaking, etc.
But I realized I never really understood the second point: why is a large B such a problem? What applications or lines of scientific inquiry does it challenge? To what degree are these challenges insurmountable?