Sr$_{0.9}$K$_{0.1}$Zn$_{1.8}$Mn$_{0.2}$As$_{2}$: a ferromagnetic semiconductor with colossal magnetoresistance

TL;DR

This study reports a new ferromagnetic semiconductor with decoupled charge and spin doping, exhibiting a Curie temperature of 12 K and colossal magnetoresistance up to -99.8% at low temperatures and magnetic fields.

Contribution

It introduces a novel bulk diluted magnetic semiconductor with decoupled charge and spin doping, showing significant ferromagnetic and magnetoresistive properties.

Findings

Ferromagnetic transition at 12 K with 1.5 μB/Mn magnetic moment.

Colossal negative magnetoresistance up to -99.8% under 5 T.

Magnetoresistance explained by Anderson localization theory.

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 $\mu_{B}$/Mn under $\mu_0H$ = 5 T and $T$ = 2 K}. Surprisingly, a colossal negative magnetoresistance, defined as $[\rho(H)-\rho(0)]/\rho(0)$, up to $-$38\% under a low field of $\mu_0H$ = 0.1 T and to $-$99.8\% under $\mu_0H$ = 5 T, was observed at $T$ = 2 K. The colossal magnetoresistance can be explained based on the Anderson localization theory.