スピネル化合物LiV_2O_4の高圧核磁気共鳴

概要

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We have developed high-pressure NMR technique with an Indenter Cell using NiCrAl alloy. It was designed to set easily into a conventional dilution fridge and/or high field magnet. We have succeeded in 7Li-NMR measurement of a heavy fermion spinel LiV2O4 in T-range between 60 mK and 30 K under pressure up to 4.7 GPa. At ambient pressure, 1/T1 shows a broad maximum around 50 K and is proportional to the temperature below 6 K. This is quite similar to the relaxation behavior in f-electron HF systems. However, 1/T1T becomes larger with applying higher pressure below 10 K and does not obey T1T = constant relation down to 1 K. Knight shift K, meanwhile, is independent of pressure above 2 GPa, indicating that the uniform component of susceptibility χ(0) does not change under high pressure. Some antiferromagnetic fluctuations with wave vector q ≠ 0 dominate relaxation rate in LiV2O4 near the boundary of the pressure induced insulating phase.
日本高圧力学会の論文
2003-11-20