Exchange interactions in R2Fe17−xGax (R=Y, Sm, Gd, Tb, Ho and Tm) compounds

We calculated the molecular field coefficients, nFeFe and nRFe (R=Sm, Gd, Tb, Ho and Tm), for R2Fe17−xGax and the values of nFeFe and nSmFe for R2Fe17−xTx (T=Al and Si) using the experimental values of the Curie temperature. The values of nFeFe increase in spite of the decrease of μFe for 0⩽x⩽5. The values of nSmFe have large values when the magnetic anisotropy is axial. For 6⩽x⩽8, the values of nFeFe, nHoFe and nTmFe increase largely, which is related to the change of the easy magnetization direction. For Y2Fe17−xTx (T=Ga and Al), the values of nFeFe have a maximum value with increasing those of μFe. With increasing V−1, the values of nFeFe have a maximum value around the same value of V−1 for Y2Fe17−xTx (T=Ga and Al). For Y2Fe17−xSix, the values of nFeFe increase with increasing V−1.