Anisotropic spin fluctuations in metallic erbium

From a μSR study of metallic erbium single crystals, the presence of anisotropic spin correlations in the paramagnetic state at temperatures well above TN has been detected. The temperature dependence of the depolarization rate of the muon precession signal gives a dynamical critical exponent of 0.15(3) for the fluctuations of the magnetic field component at the muon site that is parallel with the c-axis. For magnetic field components perpendicular to the c-axis there are no indications of slowing down of fluctuations due to the onset of spin correlations on approaching TN.