Weyl Semimetal (Experimental Realization)

First experimental realization of a Weyl semimetal, in tantalum arsenide (TaAs) -- reported essentially simultaneously by two independent groups in 2015: Xu et al. (Science 349, 613, primary landmark here) and Lv et al. (Phys. Rev. X 5, 031013, OpenAlex W2950417131).