Quasi-one-dimensional spin dynamics in LiV ₂O ₄: One-to-three-dimensional crossover as a possible origin of heavy fermion state

Spin fluctuation in LiV ₂O ₄ is revisited by examining the earlier result of muon spin rotation/relaxation measurement. Instead of the relationship for the localized electron limit, that between muon depolarization rate and spin fluctuation rate (ν _D) for itinerant electron systems is used to reanalyze data, which reveals that ν _D varies linearly with temperature (ν _D α T) over a range 10 ⁸-10 ¹² s ^-1 for 0:02 ≤ T < 10 ² K. Such a linear T behavior as well as the magnitude of ν _D is fully consistent with the behavior of magnetic relaxation rate previously observed by inelastic neutron scattering (INS), demonstrating that μSR and INS have a common time window over a fluctuation spectrum. The linear T dependence of ν _D is understood as a specific feature predicted by a Hubbard model for intersecting one-dimensional (1D) chains. This quasi-1D character, which is coexistent with enhanced uniform susceptibility at low temperatures, supports the scenario of 1D-to-3D crossover for the microscopic origin of heavy-fermion behavior in LiV ₂O ₄.