  We consider clean Dirac metals where the linear band crossing is caused by a
strong spin-orbit interaction, and study the quantum phase transitions from the
paramagnetic phase to various magnetic phases, including homogeneous
ferromagnets, ferrimagnets, canted ferromagnets, and magnetic nematics. We show
that in all of these cases the coupling of fermionic soft modes to the order
parameter generically renders the quantum phase transition first order, with
certain gapless Dirac systems providing a possible exception. These results are
surprising since a strong spin-orbit scattering suppresses the mechanism that
causes the first order transition in ordinary metals. The important role of
chirality in generating a new mechanism for a first-order transition is
stressed.
