RESUMO
By means of a specific heat (C) and electrical resistivity ([Formula: see text]) study, we give evidence of a pronounced Fermi liquid (FL) behavior with sizable mass renormalization, [Formula: see text], up to unusually high temperatures â¼70 K in the layered system (Cu2/3V1/3)V2S4. At low temperature, a marked upturn of both C and [Formula: see text] is suppressed by magnetic field, which suggests a picture of Kondo coupling between conduction electrons in the VS2 layers and impurity spins of the V3+ ions located between layers. This picture opens the possibility of controlling electronic correlations and the FL to non-FL crossover in simple layered materials. For instance, we envisage that the coupling between layers provided by the impurity spins may realize a two-channel Kondo state.
RESUMO
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 = 8.7165(7) Å, b = 15.1096(13) Å, c = 23.111(2) Å, and ß = 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 4 + valence of the V ions in the planes and a 3 + 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, χ0, 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 mΩ 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.
