Neutron Diffraction Studies on EuO

Neutron diffraction studies on EuO at various temperatures have been made at a neutron wavelength of 1.391 Å. The experimental data confirm the existence of ferromagnetism in this compound at temperatures below the Curie point (77±1°K). The intensities of the magnetic reflections vary with temperature according to the square of a Brillouin function having a spin of $\frac{7}{2}$. The magnetic scattering data also provide information on the magnetic amplitude form factor for ${\mathrm{Eu}}^{2+}$ over the region from $\frac{\left(sin\theta \right)}{\lambda }=0.17\mathrm{} \mathrm{to} 0.32$, and indicate that the form factor decreases to half-value at $\frac{\left(sin\theta \right)}{\lambda }=0.29\mathrm{}$. The nuclear scattering data of EuO show that the absolute value of the neutron coherent scattering length for Eu is $\left|f_{\mathrm{Eu}}\right|=(0.63\mathrm{}\pm 0.03)\times {10}^{-12\mathrm{}}$ cm; the experimental value for the Eu nonresonant coherent scattering length is $f_0\left(\mathrm{Eu}\right)=(0.88\mathrm{}\pm 0.04)\times {10}^{-12\mathrm{}}$ cm.