Dirac cones in a boron monolayer

2D Materials When pure boron is evaporated onto a silver substrate, a structure made up of a single layer of boron atoms can form. Several different structures have been predicted and fabricated, but it is unclear whether the electronic properties of this so-called borophene can rival those of its better known cousin graphene. Feng et al. made a sheet of boron atoms on a silver substrate that had a characteristic striped and flat structure. Although the atoms were not arranged in a hexagonal lattice, like carbon atoms are in graphene, the electronic structure of borophene showed similar linearly dispersing electronic states, called Dirac cones. The discovery may lead to applications of monolayer boron in electronic devices. Phys. Rev. Lett. 118 , 096401 (2017).