Magnetocrystalline Anisotropy of Europium Sulfide

The first- and second-order magnetocrystalline anisotropy constants, ${\mathrm{K}}_1$ and $K_2$, of EuS were measured by a ferromagnetic resonance technique. The measurements were performed at 21.48 GHz and 1.35°K, and the sample was a small, highly polished strain-free single-crystal sphere, oriented so that the (110) plane contained both the rf and static magnetic fields. The linewidth was of order 10 Oe, the narrowest observed in a chalcogenide of europium and indicates the degree of perfection and purity of the sample. $\frac{K_1}{M}$ and $\frac{K_2}{M}$ (where $M$ is the saturation magnetization) were determined to be -19.6±1.0 and -4.6±0.3 Oe, respectively. The cubic crystal-field splitting parameters $b_4$ and $b_6$ were calculated on the basis of Wolf's single-ion mechanism, and were determined to be (0.268±0.014) × ${10}^{-4\mathrm{}}$ and (-0.019±0.09) × ${10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$, respectively. The results are compared with the behavior of the ${\mathrm{Eu}}^{++}$ ion in cubic host lattices.