FMR study of Gd-Eu-Co alloy thin films

A rare earth element is doped in the Gd-Co alloy whose concentration of Co is larger than that of Gd 0.20 Co 0.80 . We prepared (Gd 1-x Co x ) 1-y Eu y alloy thin films ( x\simeq0.85, 0 \lsim y \lsim 0.10 ) by the sputtering method. Ferromagnetic resonance(FMR) was done at 300 K and at 77 K. The effective g-value at 77 K was always greater than that at 300 K and it sharply increased at 10 at.%Eu. From this result the ternary system Gd-Eu-Co remains ferrimagnetic. The linewidth \DeltaH\perp was about 2 KOe at 77 K in the vicinity of 10 at.%Eu. We applied the Tsuya-Wangsness formula to the ternary system and discussed a possible model to explain the experimental results. The Co moment decreased linearly with increasing Eu concentration because of charge transfer.