Is YbFe4Sb12 a weak ferromagnet

Abstract The magnetic susceptibility of YbFe 4 Sb 12 exhibits a strong enhancement below 30 K which suggests the presence of a ferromagnetic transition. However, the amplitude of this effect is strongly sample dependent. Furthermore, the shape of the ZFC-FC branches and the disappearance of this susceptibility increase in larger fields are rather indicative of a contribution from magnetic impurities. The magnitude of the spontaneous magnetic moment which is observed below 8–10 K is also strongly sample dependent and is likely to arises from these magnetic impurities. YbFe 4 Sb 12 remains thus probably paramagnetic down to 2 K.