Mossbauer effect and magnetization studies of YbFe4Sb12 and LaFe4Sb12

We prepared two YbFe4Sb12 samples (#1 and #2) and a LaFe4Sb12 sample. Mossbauer and magnetization measurements were performed on the samples at various temperatures and in applied magnetic fields. The experimental results indicate that #1 is in a weakly ferromagnetic state below 13 K, while #2 is in an itinerant paramagnetic state even at 2 K, and that quadrupole splitting for #1 at each temperature is slightly less than that for #2. Therefore, we conclude that YbFe4Sb12 is an intermediate material between a nearly ferromagnetic material and a weakly ferromagnetic material.