Persistent metallicity and systematic vacancies in tellurium-based quasi-one-dimensional Chevrel-type single crystals

The coexistence of structural anisotropy with building units approaching the atomic scale endows materials with unusual properties. Recently, the class of Chevrel-type chalcogenides consisting of quasi-one-dimensional (q-1D) [Mo 3 Q 3 ] n – (Q = chalcogen) chains intercalated with A + (A = alkali or main group) cations garnered renewed interest for their potential to manifest metallicity, superconductivity, and q-1D Dirac fermionic states. However, understanding their structure and properties is challenging due to their propensity to form polycrystals. Here, we demonstrate the vapor-phase-assisted synthesis of sizable crystals of a q-1D Chevrel-like crystal, In 2–δ Mo 6 Te 6 , facilitating detailed investigations of its crystal structure and electronic properties. We found from structural characterization and first-principles calculations that the distinct structure, radius ratios, and composition in In 2–δ Mo 6 Te 6 impose thermodynamically favored fractional vacancy in approximately one-eighth of In sites. In 2–δ Mo 6 Te 6 shows signatures of 1D anisotropy and persistent metallicity down to 1.7 K, despite prevailing notions that q-1D metals undergo Peierls distortion.