Anisotropy of the critical magnetic susceptibility of gadolinium

The magnetic susceptibility along the c axis (${\mathrm{\chi }}_{\mathrm{c}}$) and in the basal plane (${\mathrm{\chi }}_{\mathrm{b}}$) has been measured on a single crystal of Gd in the reduced temperature range 4×${10}^{\mathrm{-}4}$<t<1.3×${10}^{\mathrm{-}2}$. Uniaxial anisotropy is observed. Magnetic dipole-dipole interactions are shown to account for the magnitude of the uniaxial anisotropy and also to lead to complex crossover effects. The observed temperature dependence of ${\mathrm{\chi }}_{\mathrm{c}}$(T) and ${\mathrm{\chi }}_{\mathrm{b}}$(T) is described by effective exponents ${\gamma }_{\mathrm{eff}}$=1.23±0.02 and 1-${\mathrm{\alpha }}_{\mathrm{eff}}$=1.01±0.03, respectively.