Double Dirac nodal line semimetal with a torus surface state
Double Dirac nodal line semimetal with a torus surface state
We propose a class of nodal line semimetals that host an eight-fold degenerate double Dirac nodal line (DDNL) with negligible spin-orbit coupling. We find only 5 of the 230 space groups host the DDNL. The DDNL can be considered as a combination of two Dirac nodal lines, and has a …