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 Tc, 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 Tc of DyFe2Zn20 compared with that of DyRu2Zn20 is caused by this exchange interaction between the Fe and the Dy atoms.