The team highlights that Semi-Dirac fermions, a type of quasiparticle, were first theorized in 2008 and 2009 by researchers from institutions like Université Paris Sud in France and the University of California, Davis. These quasiparticles were predicted to have a mass that varies with their direction of motion—massless in one direction but massive in another.
Sixteen years after this prediction, researchers led by Shao and colleagues accidentally observed semi-Dirac fermions using magneto-optical spectroscopy.
The technique shines infrared light on a material under a strong magnetic field and analyzes the reflected light. While studying silver-colored crystals of ZrSiS, the team unexpectedly confirmed the existence of these long-theorized quasiparticles.