Spin fluctuations in a magnetically frustrated metal, LiV2O4

Abstract

Inelastic neutron scattering is used to characterize spin fluctuations in the $d$-electron heavy fermion spinel $\rm LiV_2O_4$. The spin relaxation rate, $Γ_Q$, for $Q=0.6$ Å$^{-1}$ is 1.5(1) meV at low temperatures and increases linearly with temperature at a rate of 0.41(4) k$_B$. There is antiferromagnetic short range order at low temperatures with a characteristic wave vector $Q_c= 0.64(2)$ Å$^{-1}$ and a correlation length of 6(1) Å. Warming shifts intensity towards lower $Q$ so that magnetic scattering decreases monotonically with $Q>0.3$ Å$^{-1}$ for $T>40$ K. The data are compared with conventional heavy fermion systems, geometrically frustrated insulating magnets, and recent theories for $\rm LiV_2O_4$.