Enhanced Paramagnetism and Spin Fluctuations in Expanded Liquid Cesium

Abstract

$^{133}\mathrm{Cs}$ NMR has been used to probe the volume-dependent static and dynamic spin susceptibility of expanded liquid cesium. Data taken over the temperature range 55-1400\ifmmode^\circ\else\textdegree\fi{}C cover the density range $1.03<\ensuremath{\rho}<1.92$ g ${\mathrm{cm}}^{\ensuremath{-}3}$. For $\ensuremath{\rho}\ensuremath{\lesssim}1.5$ g ${\mathrm{cm}}^{\ensuremath{-}3}$, both the isobaric temperature dependence and the isothermal pressure dependence of the Knight shift change sign and the spin susceptibility becomes increasingly enhanced. Analysis of the nuclear relaxation rates at low densities indicates changes in the $q$-dependent susceptibility suggestive of a metallic antiferromagnet above its ordering temperature.