Neutron Diffraction Investigation of a Gadolinium Single Crystal

A single-crystal disk of Gd cut parallel to (00.1) has been studied in zero magnetic field. A careful search along and perpendicular to the c* axis in the neighborhood of the (00.2) reflection has failed to reveal any satellites in the temperature range 77° to 290°K. Thus unlike the rare-earth elements from Tb to Tm, gadolinium is a normal ferromagnet. Above 248°K, the moment is aligned along the c axis. Below this temperature, the moments make an angle with the c axis which reaches a maximum of 75° at 195°K and approaches 30° at 4°K. The coherent nuclear scattering amplitude has been estimated by scaling the nuclear scattering to the magnetic scattering in the (00.2) reflection. The result is |b|=1.5±0.2×10−12 cm.