We consider a stable ordered CuPt-structure at x = 0.5 with alternating (111)-layers of As and Sb. Experimental evidence for the CuPt-ordering of InA0.5Sb0.5 exists.9-13 Furthermore, we find an inverted band ordering realizing a novel type of topological semimetall14-17 with triple degeneracy points.18 We identify the novel semimetal as having both properties of the established topological Dirac 19-21 and Weyl15, 22 semimetals, and thus the triple point can be seen as an interpolation of Dirac and Weyl points. Analog to the Dirac and Weyl semimetals we find surface Fermi arcs19, 21, 23-27 and anomalous transport in the presence of magnetic fields. 28-30
The band inversion can be avoided either by application of experimentally achievable strain or incomplete ordering making the CuPt-ordered InA0.5Sb0.5 a semiconductor with a large intrinsic linear in k bulk spin splitting in the conduction bands. Furthermore, we find large Landé g-factors for thin films of CuPt-ordered InA0.5Sb0.5, which is crucial for the realization of various Majorana scenarios.1, 2, 31, 32 In conclusion, the electronic properties of CuPt-ordered InA0.5Sb0.5 outperform all presently available Majorana platforms.