Dirac materials, unlike the Weyl materials, have not been found in experiments to support intrinsic topological surface states, as the surface arcs in existing systems are unstable against symmetry-preserving perturbations. Utilizing the proposed glide and time-reversal symmetries, we theoretically design and experimentally verify an acoustic crystal of two frequency-isolated three-dimensional Dirac points with Z2 monopole charges and four gapless helicoid surface states.
@article{arxiv.2001.06205,
title = {Discovering topological surface states of Dirac points},
author = {Hengbin Cheng and Yixin Sha and Rongjuan Liu and Chen Fang and Ling Lu},
journal= {arXiv preprint arXiv:2001.06205},
year = {2020}
}