Magnetocrystalline Anisotropy of Europium Sulfide

The first- and second-order magnetocrystalline anisotropy constants, K₁ and K₂, 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. K₁M and K₂M (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 b₄ and b₆ were calculated on the basis of Wolf's single-ion mechanism, and were determined to be (0.268±{}0.014) ×{} 10^-4 and (-0.019±{}0.09) ×{} 10^-4 cm^-1, respectively. The results are compared with the behavior of the Eu⁺⁺ ion in cubic host lattices.