Weak localization and Mott state in two-dimensional Sr3V5S11
Résumé
We report on the high-pressure synthesis, structural study and physical properties of a new layered compound, Sr3V5S11. Single-crystals of 0.3 mm size were synthesized at the optimized growth conditions of 6 GPa and 1600 C. The refinement of x-ray diffraction data indicates that the crystal structure is monoclinic (space group C2=c), with cell parameters a D 8:7165.7/ A° , b D 15:1096.13/ A° , c D 23:111.2/ A° , and D 98:734.9/. The structure consists of a stacking of VS2 layers with a CdI2-type structure within the ab-plane connected by trimers of face-sharing VS6 octahedra oriented along the out-of-plane direction. Salient features are a 4C valence of the V ions in the planes and a 3C valence in the trimers and a large stripe-like modulation of the V-V distances in the planes leading to quasi-one-dimensional properties. The magnetic susceptibility displays a large temperature-independent contribution, 0, in addition to a moderate Curie-Weiss term. In the 300-120 K range, the electrical resistivity is described well by a semiconducting-like behaviour with a room-temperature value of 1.2-10 m cm and a modest activation energy of 13.5 meV. At lower temperatures, a crossover to a one-dimensional variable range hopping regime is observed, supporting a scenario of a correlated 1D system.
Mots clés
High-pressure effects in solids and liquids
Inorganic compounds 81.05.-t Specific materials: fabrication
treatment
testing and analysis
Metal-insulator transitions and other electronic transitions
Saturation moments and magnetic susceptibilities Theory of crystal structure
crystal symmetry
calculations and modeling