Mössbauer Study of Metamagnetic Eu3O4 and Ferromagnetic EuO

The Mössbauer technique has been employed to study the metamagnetic oxide Eu₃O₄ and the ferromagnet EuO. In Eu₃O₄ both di‐ and trivalent europium ions are present (in the ratio 1:2) with isomer shifts at 77°K of −1.25±0.02 and +0.06±0.02 cm/sec, respectively. In the helium temperature range the divalent ions in Eu₃O₄ showed magnetic hfs, with a hyperfine field of 305±8 kOe at 1.2°K. The temperature dependence of the magnetic hfs of the Eu_i⁺ nuclei was followed from 1.2°K to the zero magnetic field Néel point of 6.2±0.2°K determined during these measurements. The data are only modestly well approximated by a Brillouin function with $\mathrm{J=}\frac{7}{2}$ . No hfs was found at the trivalent side. In EuO, the temperature dependence of the hyperfine field was followed from 77° to 4.2°K. The data are compared with predictions of two models for a cubic ferromagnet.