Neutron diffraction study on magnetic properties of anhydrous gadolinium trichloride

Abstract

Elastic neutron scattering from a single crystal of hexagonal ¹⁶⁰GdCl₃ was measured at liquid helium temperatures with neutron wavelengths of 1.45 and 2.36 AA. Large extinction was observed and analysed in terms of a recent theory developed by Becker and Coppens (1974-75). The strongest reflections were reduced by primary and secondary extinction by 2 and 80 per cent respectively. From magnetic Bragg intensities ((101) and (112)) in the temperature range 0.002c identical to epsilon <or=0.07 the critical behaviour of the spontaneous magnetization was derived. The epsilon -dependence of the magnetization was explained by a power law with an exponent of 0.43+or-0.02 and an amplitude of 1.40+or-0.10, or with the same accuracy by a modified mean-field law predicted for the group of uniaxial dipolar ferromagnets.