Neutron Diffraction Studies on Europium Metal

Abstract

Neutron diffraction investigations have been made on metallic europium which show the metal to be antiferromagnetic with a Néel temperature of 87°±1°K. The observed magnetic reflections can be interpreted in terms of a helical spin structure having a pitch of 3.60 a₀ and a helix axis in the (100) direction or an amplitude modulated structure in the (100) direction having a periodicity of 3.60 a₀. Between 20° and 87°K, within experimental error, the intensities of the magnetic reflections are proportional to (T_N—T)^½, where T_N is the Néel temperature. The helix pitch is not a function of temperature.