Table 1.
The classification of type-I and type-II Dirac/Weyl semimetal
| Classification | Type I | Type II | |
|---|---|---|---|
| Lorentz invariant | Breaking Lorentz invariance | ||
| Dirac | Protected by crystal symmetry | Na3Bi8, 12 | PtTe2 (this work) |
| Doubly-degenerate Dirac cone | Cd3As2 9, 13 | ||
| Closed surface from TSS | |||
| Weyl | Breaking time-reversal or inversion symmetry | TaAs family10, 11 | MoTe2 14, 15 |
| Non-degenerate Dirac cone | |||
| Open Fermi arcs from TSS | |||
| Electronic and transport properties | Linear Dirac cone | Strongly tilted Dirac cone | |
| Isolated Dirac/Weyl points with vanishing DOS at E F | Dirac/Weyl points at the touching of electron and hole pockets | ||
| Negative magneto-resistance along all direction | Anisotropic, negative magneto-resistance along certain direction |