Topological semimetals have attracted extensive research interests for realizing condensed matter physics counterparts of three-dimensional Dirac and Weyl fermions, which were originally introduced in high energy physics. Recently it has been proposed that type-II Dirac semimetal can host a new type of Dirac fermions which break Lorentz invariance and therefore does not have counterpart in high energy physics. Here we report the electronic structure of high quality PtSe2 crystals to provide direct evidence for the existence of three-dimensional type-II Dirac fermions. A comparison of the crystal, vibrational and electronic structure to a sister compound PtTe2 is also discussed. Our work provides an important platform for exploring the novel quantum phenomena in the PtSe2 class of type-II Dirac semimetals.
@article{arxiv.1703.04242,
title = {Experimental evidence of type-II Dirac fermions in PtSe2},
author = {Kenan Zhang and Mingzhe Yan and Haoxiong Zhang and Huaqing Huang and Masashi Arita and Zhe Sun and Wenhui Duan and Yang Wu and Shuyun Zhou},
journal= {arXiv preprint arXiv:1703.04242},
year = {2017}
}