Sr0.9K0.1Zn1.8Mn0.2As2: A ferromagnetic semiconductor with colossal magnetoresistance

A bulk diluted magnetic semiconductor (Sr,K)(Zn,Mn)2As2 was synthesized with decoupled charge and spin doping. It has a hexagonal CaAl2Si2-type structure with the (Zn,Mn)2As2 layer forming a honeycomb-like network. Magnetization measurements show that the sample undergoes a ferromagnetic transition with a Curie temperature of 12 K and magnetic moment reaches about under and . Surprisingly, a colossal negative magnetoresistance, defined as , up to under a low field of and to under , was observed at . The colossal magnetoresistance can be explained based on the Anderson localization theory.