Compton scattering study of 4fmagnetism inCeFe2

Magnetic Compton scattering, which measures solely the electron spin moment, has been used to provide direct evidence for the low value of the 4f moment on cerium in the ferrimagnetic compound ${\mathrm{CeFe}}_2$. The measurements were performed by using monochromatic, 61.34 keV photons with a high degree of circular polarization produced by an elliptical multipole wiggler at the Accumulation Ring Source, KEK, Japan. Analysis of the Compton profile shows the 4f spin moment to be antiparallel to the moment on Fe. This is consistent with the 4f moment as deduced from neutron-diffraction data yet conflicts markedly with the moment predicted in a series of ab initio band calculations, being less than half the calculated value of 0.42${\mathrm{\mu }}_{\mathit{B}}$. © 1996 The American Physical Society.