Possible phase separation and weak localization in the absence of a charge-density wave in single-phase 1 T-VS 2

We report on a systematic study of the structural, magnetic, and transport properties of high-purity 1T -VS2powder samples prepared under high pressure. The results differ notably from those previously obtained bydeintercalating Li from LiVS2. First, no charge-densitywave (CDW) is found by transmission electronmicroscopydown to 94 K, though ab initio phonon calculations unveil a latent CDW instability driven by an acousticphonon softening at the wave vector qCDW? (0.21,0.21,0) previously reported in deintercalated samples. Afurther indication of latent lattice instability is given by an anomalous expansion of the V-S bond distanceat low temperature. Second, infrared optical absorption and electrical resistivity measurements give evidenceof nonmetallic properties, consistent with the observation of no CDW phase. On the other hand, magneticsusceptibility and NMR data suggest the coexistence of localized moments with metallic carriers, in agreementwith ab initio band structure calculations. This discrepancy is reconciled by a picture of electron localizationinduced by disorder or electronic correlations leading to a phase separation of metallic and nonmetallic domainsin the nm scale.We conclude that 1T -VS2 is at the verge of a CDWtransition and suggest that residual electronicdoping in Li deintercalated samples stabilizes a uniform CDW phase with metallic properties.