Spin fluctuations probed by NMR in paramagnetic spinel LiV2O4: a self-consistent renormalization theory
Abstract
Low frequency spin fluctuation dynamics in paramagnetic spinel LiV2O4, a rare 3d-electron heavy fermion system, is investigated. A parametrized self-consistent renormalization (SCR) theory of the dominant AFM spin fluctuations is developed and applied to describe temperature and pressure dependences of the low-T nuclear spin-lattice relaxation rate 1/T1 in this material. The experimental data for 1/T1 available down to 1K are well reproduced by the SCR theory, showing the development of AFM spin fluctuations as the paramagnetic metal approaches a magnetic instability under the applied pressure. The low-T upturn of 1/T1T detected below 0.6 K under the highest applied pressure of 4.74 GPa is explained as the nuclear spin relaxation effect due to the spin freezing of magnetic defects unavoidably present in the measured sample of LiV2O4.