Dirac semimetal to Weyl semimetal*

Dirac and Weyl semimetals have attracted much attention in the past few years. The Dirac compound Cd₃As₂ has seen renewed interest due to reports of proximity-induced surface superconductivity [1] and quantum Hall effect in thin films [2]. Using first-principles based theoretical methods, we show that by breaking time-reversal symmetry upon the application of an external Zeeman magnetic field, the four-fold degenerate Dirac node in Cd₃As₂ splits into four non-degenerate Weyl nodes, of which two are simple Weyl nodes of chirality ±1 and other have chiral charges of ±2. We calculate the evolution of the Fermi surfaces and their contributions to the anomalous Hall conductivity as a function of magnetic field and Fermi level position. Our work forms a basis for understanding how the resulting hole and electron pockets may play a role in generating complex states such as unconventional forms of superconductivity.
References:
1. Ce Huang et al, Nature Communications 10, 2217 (2019)
2. Shinichi Nishihaya et al, Nature Communications 10, 2564 (2019)