Field and Temperature Dependence of 153Eu Spin-Lattice Relaxation in Ferromagnetic EuO

Nuclear spin‐lattice relaxation times, T₁, of ¹⁵³Eu have been measured in an irregularly shaped single crystal of EuO over the temperature range of ${\text{1.2}}^{\circ }{\text{≦T≦4.2}}^{\circ }\mathrm{K}$ and magnetic field range of ${\text{0≦H}}_0\text{≦14\hspace{0.17em}}\mathrm{kOe}$ for the crystal orientation $H_0{\mathrm{\perp H}}_{\mathrm{rf}}\text{∥〈110〉}$ by use of the spin‐echo technique. The relaxation process was found to satisfy T₁ ∝ T⁻ⁿ, where n increases from approximately 2–3 as H₀ increases from zero to 10 kOe. The T₁ is essentially field independent up to H₀≈2 kOe, Above this field there is a general increase in T₁ but with an intermediate peak value at H₀≈6 kOe. The analysis of these data is complicated by the irregular shape of the sample and the high saturation magnetization, 4πM₀=24 kOe, for EuO. Within these limitations these results have been compared with the theory developed by Honma for EuS.