Self-consistent renormalization theory of spin fluctuations in paramagnetic spinel LiV2O4

Abstract

A phenomenological description for the dynamical spin susceptibility ( q,ω;T) observed in inelastic neutron scattering measurements on powder samples of LiV2O4 is developed in terms of the parametrized self-consistent renormalization (SCR) theory of spin fluctuations. Compatible with previous studies at T 0, a peculiar distribution in q-space of strongly enhanced and slow spin fluctuations at q Qc 0.6 -1 in LiV2O4 is involved to derive the mode-mode coupling term entering the basic equation of the SCR theory. The equation is solved self-consistently with the parameter values found from a fit of theoretical results to experimental data. For low temperatures, T 30K, where the SCR theory is more reliable, the observed temperature variations of the static spin susceptibility (Qc;T) and the relaxation rate Q(T) at q Qc are well reproduced by those suggested by the theory. For T 30K, the present SCR is capable in predicting only main trends in T-dependences of (Qc;T) and Q(T). The discussion is focused on a marked evolution (from q Qc at T 0 towards low q values at higher temperatures) of the dominant low-ω integrated neutron scattering intensity I(q; T).