Giant hyperfine field on151Eu in EuFe4P12(Mossbauer study)

Abstract

Unusual ¹⁵¹Eu²⁺ hyperfine parameters are observed in EuFe₄P₁₂. The low-temperature saturated hyperfine field (H=-670 kOe) is particularly large and the isomer shift of -6.0 mm s^-1 (relative to EuF₃) is evidence of a particularly high nuclear s-electron density. In addition, the ferromagnetic ordering temperature is very high (100K) especially in view of the large distance (6.8 AA) between the Eu²⁺ ions and the fact that Fe has no localised magnetic moment. The anomalously high hyperfine field points to the importance of f-d band coupling.