Exploring elusive high-energy particles in an unusual metal
Mid-infrared wavelengths of light are invisible to the eye but can be useful for a number of technologies, including night vision, thermal sensing, and environmental monitoring. Now, a new phenomenon in an unconventional metal, found by physicists at MIT and elsewhere, could provide a new way of making highly sensitive detectors for these elusive wavelengths. The phenomenon is closely related to a particle that has been predicted by high-energy physicists but never observed. Physicists group all the fundamental particles in nature into two categories, fermions and bosons, according to a property called spin. The fermions, in turn, have three types: Dirac, Majorana, and Weyl. Dirac fermions include the electrons in regular metals such as copper or gold. The other two are unconventional particles that can give rise to strange and fundamentally new physics, which potentially can be used to build more efficient circuits and other devices. The Weyl fermion was first theorized...