Coexistence of Type-I and Type-II Weyl Points in the Weyl-Semimetal OsC2

Abstract

The topologically nontrivial Weyl semimetals have two different types: (i) the standard Weyl cones with point-like Fermi surfaces (type-I) and (ii) tilted Weyl cones that appear at the contact of electron and hole pockets (type-II). These two types of Weyl semimetals have significantly different physical properties in their thermodynamics and magnetotransport. Here we presented a compound OsC2 with both types Weyl points (WPs) at the equilibrium volume. It has 24 type-I WPs in the Kz = ±0.0241 ×2πc planes around K (or K′) points and 12 type-II WPs in the Kz = ±0.4354 ×2πc planes at the projected K (K′) point, respectively. The type-I WPs are connected by the helix-trimer Fermi arcs.