Li NMR in LiV₂O₄ under high pressure

The Knight shift K and the nuclear spin-lattice relaxation time T₁ of ⁷Li have been measured under high pressure up to 4.74 GPa. 1/T₁T becomes larger on applying higher pressure below 10 K and does not obey the T₁T = constant relation down to 1 K. Meanwhile, K is independent of pressure above 2 GPa, indicating that the uniform component of the susceptibility does not change under high pressure. These results indicate that some antiferromagnetic fluctuations with wavevector q ≠ 0 dominate the relaxation rate in LiV₂O₄ near the boundary of the pressure induced insulating phase. It is noted that the pressure dependence of T₁ for LiV₂O₄ is opposite to that of typical Ce HF compounds, such as CeCu_5.9Au_0.1 and CeCu₂Si₂. At the highest pressure of 4.74 GPa, we found that 1/T₁ obeys a power law dependence of T^2/3 over the wide T range between 60 mK and 10 K. The spin dynamics under high pressure will be discussed.