Enhancement of Curie temperature due to the coupling between Fe itinerant electrons and Dy localized electrons in DyFe2Zn20
The temperature dependence of magnetization and specific heat of the ferromagnetic compound DyFe2Zn20 has been measured in detail in various magnetic fields. We have observed anomalous magnetic behavior, i.e., a strong anisotropy at 2 K, disappearance of this anisotropy between approximately 30 K and T_c, and anomalous behavior of the specific heat in the magnetic fields 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, 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 Dy atoms.