Neutron diffraction and scattering study of the weak ferromagnetism inNaFe4Sb12skutterudite

Abstract

A structural and magnetic investigation of ${\mathrm{NaFe}}_{4}{\mathrm{Sb}}_{12}$ with filled skutterudite structure is carried out by means of powder neutron diffraction and magnetization measurements in order to investigate the magnetic ground state of this compound. The existence of an ordered magnetic moment on the Fe site of $\ensuremath{\approx}0.6{\ensuremath{\mu}}_{B}$/Fe atom is in good agreement with magnetization data. The ratio between the number of spins in the paramagnetic state and in the saturated ferromagnetic state is $\ensuremath{\approx}1.7$, indicating some degree of delocalization of the Fe magnetic moment in ${\mathrm{NaFe}}_{4}{\mathrm{Sb}}_{12}$. Theoretical density-functional calculations of real-space spin-density maps are performed and compared to the experimental findings of weak ferromagnetism in ${\mathrm{NaFe}}_{4}{\mathrm{Sb}}_{12}$ (${T}_{C}\ensuremath{\approx}83$ K). Diffuse magnetic scattering with polarized neutrons revealed that a localized moment exists in the paramagnetic phase which decreases with increasing temperature. The results are discussed in the light of comparison with other intermetallic compounds.