Metallic Spin Liquid-like Behavior of LiV${}_2$O${}_4$

LiV${}_2$O${}_4$ spinel is known to exhibit heavy fermion-like behavior below a characteristic temperature $T_K\simeq 20$ K, while it preserves a paramagnetic state down to $T\sim {10}^{-2}$ K due to geometrical frustration. Here, it is shown that the dynamical spin susceptibility $\chi (\mathbf{q},\omega )$ in LiV${}_2$O${}_4$ exhibits anomalous duality which is modeled as a sum of itinerant (${\chi }_{\mathrm{F}}$) and local (${\chi }_{\mathrm{L}}$) components,and that the local spin dynamics inferred from ${\chi }_{\mathrm{L}}(\mathbf{q},\omega )$ is qualitatively different from that expected from time-averaged bulk properties. The anomaly coexists with the marginal Fermi liquid behavior inferred from the $-\ln T$ dependence of the electronic specific heat over a wide temperature range below $T_K$. We argue that such unusual properties of LiV${}_2$O${}_4$ can be attributed to the putative metallic spin liquid state emerging near the quantum critical point between spin glass and Fermi liquid states.