Giant magnetoresistance in oxypnictides (La,Nd)OMnAs

A sizeable negative magnetoresistance (MR) has been observed for oxypnictides LnOMnAs (Ln = La,Nd). MR up to −24% is observed at 200 K for LaOMnAs which is unprecedented for divalent Mn2+. Both materials are weak ferromagnets with transition temperatures above room temperature.