Spin-glass-like behavior in SmFeAsO0.8F0.2

The iron-based oxypnictide superconductor SmFeAsO0.8F0.2 was synthesized\nunder high-pressure and investigated by measuring dc magnetic susceptibility.\nThe zero-field cooled (ZFC) magnetic susceptibility confirmed the bulk\nsuperconductivity of the sample with a critical temperature of Tc = 50 K and a\nsignificant jump in the magnetization at 4.3 K, usually attributed to the\nantiferromagnetic ordering of Sm3+ ions in this system. Since the occurrence of\nthe jump depends on the cooling history, our data strongly suggest a\nspin-glass-like behaviour.\n