The interactions of quasiparticles can be described by renormalizing their masses, such that some materials have a vanishingly small effective mass, whereas others have a very high effective mass. The observation by Vyalikh and colleagues of both extremes occurring on the surface and interior of the same material offers a new view of many-body interactions.
- M. Höppner
- S. Seiro
- D. V. Vyalikh
