Heavy-Fermions in LiV2O4: Kondo-Compensation vs. Spin-Liquid Behavior?
  7Li NMR measurements were performed in the metallic spinel LiV2O4. The temperature dependencies of the line width, the Knight shift and the spin-lattice relaxation rate were investigated in the temperature range 30 mK < T < 280 K. For temperatures T < 1 K we observe a spin-lattice relaxation rate which slows down exponentially. The NMR results can be explained by a spin-liquid behavior and the opening of a spin gap of the order 0.6 K. 
H. Kaps, N. B\"uttgen, W. Trinkl, A. Loidl, M. Klemm, and S. Horn