  Transition metal halides can host a large variety of novel phenomena, such as
magnetism in the monolayer limit, quantum spin liquid and spiral spin liquid
states, and topological magnons and phonons. Sizeable high quality single
crystals are necessary for investigations of magnetic and lattice excitations
by, for example, inelastic neutron scattering. In this paper, we review a less
well-known vapor transport technique, self-selecting vapor growth, and report
our growths of transition metal halides using this technique. We report the
growth and characterizations of sizable single crystals of RuCl$_3$, CrCl$_3$,
Ru$_{1-x}$Cr$_x$Cl$_3$, and CrBr$_3$. In order to expedite the conversion of
starting powder to single crystals, we modified the technique by cooling the
growth ampoule through an appropriate temperature range. Our work shows that
the self-selecting vapor transport technique can provide large single crystals
of transition metal halides, demonstrating its potential for providing high
quality single crystals of quantum materials.
