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 -VS2 powder samples prepared under high pressure. The results differ notably from those previously obtained by deintercalating Li from LiVS2. First, no charge-densitywave (CDW) is found by transmission electronmicroscopy down to 94 K, though ab initio phonon calculations unveil a latent CDW instability driven by an acoustic phonon softening at the wave vector qCDW ? (0.21,0.21,0) previously reported in deintercalated samples. A further indication of latent lattice instability is given by an anomalous expansion of the V-S bond distance at low temperature. Second, infrared optical absorption and electrical resistivity measurements give evidence of nonmetallic properties, consistent with the observation of no CDW phase. On the other hand, magnetic susceptibility and NMR data suggest the coexistence of localized moments with metallic carriers, in agreement with ab initio band structure calculations. This discrepancy is reconciled by a picture of electron localization induced by disorder or electronic correlations leading to a phase separation of metallic and nonmetallic domains in the nm scale.We conclude that 1T -VS2 is at the verge of a CDWtransition and suggest that residual electronic doping in Li deintercalated samples stabilizes a uniform CDW phase with metallic properties.