Self-selecting vapor growth of transition-metal-halide single crystals

Abstract

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, topological magnons, and chiral phonons. Sizable 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 $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{RuCl}}_{3}, {\mathrm{CrCl}}_{3}, {\mathrm{Ru}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{Cl}}_{3}$, and ${\mathrm{CrBr}}_{3}$. 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.