After the observation of topological insulator, quantum anomalous Hall effect, and Weyl fermion, researchers from the Institute of Physics (IOP) of CAS used angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification.
Their experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems. The whole process in this study, from theoretical prediction to material synthesis and experimental confirmation, was completed by Chinese researchers independently.
This work was published in Nature on June 19th, 2017.