Valley nematics: Unfinished bismuth

Zhu et al report report anisotropies characteristic of orientational order in the conductivity of a three-dimensional sample of bismuth with three nominally degenerate valleys, suggesting a breaking of valley symmetry. Although the recent discovery of topological features in the electronic structure of insulators closely related to bismuth has contributed to a revival of experimental and theoretical interest in the properties of the elemental metal itself, the observation of interaction-induced valley symmetry breaking would still warrant signicant excitement.