Ferromagnetic heavy fermion behavior in filled skutterudite compound SmFe4P12 by 31P-NMR

Abstract We have carried out the 31 P-NMR measurements on the filled skutterudite compound SmFe 4 P 12 , and observed the ferromagnetic heavy fermion behavior. The 31 P-NMR spectra show that the system remains in the paramagnetic state above the Curie temperature T C . The temperature T and the applied magnetic field dependences of the spin-lattice relaxation rate 1/ T 1 indicate the heavy fermion behavior (1/ T 1 T ∼constant) in the range of T =7.5–25 K and the ferromagnetic fluctuations of the Sm moments above the T C .