Anomalous surface states with Fermi arcs are commonly considered to be a fingerprint of Dirac semimetals (DSMs). In contrast to Weyl semimetals, however, Fermi arcs of DSMs are not topologically protected. Using first-principles calculations, we predict that β-CuI is a peculiar DSM whose surface states form closed Fermi pockets instead of Fermi arcs. In such a fermiological Dirac semimetal, the deformation mechanism from Fermi arcs to Fermi pockets stems from a large cubic term preserving all crystal symmetries, and the small energy difference between the surface and bulk Dirac points. The cubic term in β-CuI, usually negligible in prototypical DSMs, becomes relevant because of the particular crystal structure. As such, we establish a concrete material example manifesting the lack of topological protection for surface Fermi arcs in DSMs
@article{arxiv.1801.05719,
title = {$\beta$-CuI: a Dirac semimetal without surface Fermi arcs},
author = {Congcong Le and Xianxin Wu and Shengshan Qin and Yinxiang Li and Ronny Thomale and Fuchun Zhang and Jiangping Hu},
journal= {arXiv preprint arXiv:1801.05719},
year = {2020}
}