Neutron Diffraction Investigations of Metallic Cerium at Low Temperatures

Neutron diffraction experiments have been performed on metallic cerium at a series of temperatures between room temperature and 4.2^∘{}K in an attempt to clarify the anomalous behavior which has been observed in previous specific-heat and magnetic-susceptibility measurements. Results on three specially prepared samples show that the interesting magnetic behavior can be correlated with the three crystallographic phases present in the samples. There is a change in the electronic configuration of the cerium atoms when the collapsed face-centered cubic phase is formed, and antiferromagnetic ordering occurs in the hexagonal close-packed phase at about 12.5^∘{}K.