A massless particle, a.k.a. Weyl fermion, predicted nearly 100 years ago, has been found in another corner of physics. Electrons in a semimetal can behave like these particles. They are either right-handed or left-handed—they are mirror images like our hands. Theory predicted that Weyl semimetals could produce handedness-dependent electrical current by shining circularly polarized infrared … Continue reading Current generated when light hits a material reveals electrons behaving like an elusive particle