Enhancement of the curie temperature due to the coupling between Fe itinerant electrons and Dy localized electrons in DyFe₂Zn₂₀

The temperature dependences of the magnetization and the specific heat of the ferromagnetic compound DyFe₂Zn₂₀ have been measured in detail in various magnetic fields. We have observed anomalous magnetic behaviors, i.e., a strong anisotropy at 2 K, the disappearance of this anisotropy at temperatures between approximately 30 K and T _c, and an anomalous behavior of the specific heat in magnetic fields at temperatures near 20 K. These anomalous phenomena have been analyzed based on the strong exchange interaction between the Fe itinerant electrons and the Dy localized electrons, as well as the crystalline electric field, the Zeeman energy, and an usual exchange interaction between two Dy atoms. The higher T _c of DyFe₂Zn₂₀ compared with that of DyRu₂Zn₂₀ is caused by this exchange interaction between the Fe and the Dy atoms.