7Li NMR studies in magnetically frustrated LiV2O4: Evidence for a spin-liquid ground state?

7Li NMR measurements were performed in the metallic spinel LiV2O4. The temperature dependence of the spin-lattice relaxation rate is documented in the temperature range 100 mK < T < 280 K. A comparison with the spin-glass behavior of Li1–xZnxV2O4 for small concentrations of x is given. For low temperatures T < 1 K we observe a maximum for the spinlattice relaxation rate in LiV2O4. The frequency dependence of this maximum is indicative for a slowing down of spin fluctuations. The NMR results can be explained by a spin-liquid behavior and the opening of a spin gap of the order 1 K.