  We study polycrystalline samples of the hexagonal pnictides, CaAgP and
CaAgAs, both of which are ideal candidates for line-node Dirac semimetals. The
polycrystalline samples of CaAgP and CaAgAs obtained in this study are
low-carrier metals, where hole carriers are dominant. By combining the hole
carrier densities estimated from Hall coefficients and the electronic
structures calculated by first principles calculations, both samples are found
to have a ring-torus Fermi surface, derived from a ring-shaped Dirac line node.
In the phosphide sample, the Fermi energy EF is located at around the end of
the linear dispersion region of the electronic bands, while the EF in the
arsenide sample exists in the middle of this region, suggesting that the
arsenide is a more promising system for uncovering the physics of line-node
Dirac semimetals.
