Sr${}_{0.9}$K${}_{0.1}$Zn${}_{1.8}$Mn${}_{0.2}$As${}_2$: a ferromagnetic semiconductor with colossal magnetoresistance

Abstract

A bulk diluted magnetic semiconductor (Sr,K)(Zn,Mn)${}_2$As${}_2$ was synthesized with decoupled charge and spin doping. It has a hexagonal CaAl${}_2$Si${}_2$-type structure with the (Zn,Mn)${}_2$As${}_2$ layer forming a honeycomb-like network. Magnetization measurements show that the sample undergoes a ferromagnetic transition with a Curie temperature of 12 K and \revision{magnetic moment reaches about 1.5 $\hat{I}{¼}_B$/Mn under $\hat{I}{¼}_{0}H$ = 5 T and $T$ = 2 K}. Surprisingly, a colossal negative magnetoresistance, defined as $[\ddot{I}(H)-\ddot{I}(0)]/\ddot{I}(0)$, up to $-$38\% under a low field of $\hat{I}{¼}_{0}H$ = 0.1 T and to $-$99.8\% under $\hat{I}{¼}_{0}H$ = 5 T, was observed at $T$ = 2 K. The colossal magnetoresistance can be explained based on the Anderson localization theory.

Accepted for publication in EPL