Coexistence of superconductivity and antiferromagnetic ordering in the layered superconductor SmFePO

Abstract

Superconductivity and magnetic transition in SmFePO were examined by electric, magnetic, F 57 e Mössbauer, and S 149 m nuclear resonant forward-scattering (NRFS) measurements. Zero resistivity and negative magnetic susceptibility were observed in an undoped SmFePO, indicating superconducting transition temperature (Tc) of ∼3 K. Tc in undoped SmFePO appears in a narrow region of lattice constants with an optimum conductivity. Furthermore, in relation to magnetic susceptibility, NRFS spectra verify that magnetic moments of Sm3+ ions order antiferromagnetically below magnetic transition ∼5 K, accompanying a discontinuous drop in electrical resistivity, whereas F 57 e Mössbauer spectra show that magnetic moments of Fe are quenched. These results indicate the coexistence of superconductivity and magnetic ordering in a crystallographic unit cell of SmFePO. © 2008 The American Physical Society.