Weyl semimetal (WSM) can be classified into type-I, which respects Lorentz symmetry, and type-II, which does not. In a type-II WSM, the Weyl cone exhibits strong tilting so that the Weyl point appears as the contact point between an electron pocket and a hole pocket in the Fermi surface. Recently we have predicted the layered transition-metal dichalcogenides MoTe2 as the material candidate of type-II WSM [1]. Soon after our prediction, MoTe2 has been verified as the first type-II WSM by ARPES experiments from several independent groups [2-7].
References:
- Sun, Y., Wu, S.-C., Ali, M. N., Felser, C. & Yan, B. Prediction of Weyl semimetal in orthorhombic MoTe2. Phys. Rev. B 92, 161107 (2015).
- Deng, K. et al. Experimental observation of topological Fermi arcs in type-II Weyl semimetal MoTe2. Nature Physics 12, 1105–1110 (2016).
- Huang, L. et al. Spectroscopic evidence for a type II Weyl semimetallic state in MoTe2. Nature Materials 15, 1155–1160 (2016).
- Jiang, J. et al. Signature of type-II Weyl semimetal phase in MoTe2. Nature Commun. 8, 13973 (2017).
- Tamai, A. et al. Fermi Arcs and Their Topological Character in the Candidate Type-II Weyl Semimetal MoTe2. Phys. Rev. X 6, 031021 (2016).
- Liang, A. et al. Electronic Evidence for Type II Weyl Semimetal State in MoTe2. arXiv:1604.01706 (2016).
- Sakano, M. et al. Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe2. Phys. Rev. B 95, 121101 (2017).