Colossal linear magnetoresistance in a CdGeAs2:MnAs micro-composite ferromagnet

The magnetic properties of a Cd1−xMnxGeAs2: MnAs hybrid micro-composite have the signature of ferromagnetic order at room temperature. Magnetotransport reveals the presence of a large linear positive magnetoresistance, with maximum values of about 550% (B=22B=22 T) for x=0.028x=0.028. This is interpreted in terms of an effective medium approximation with the value and the shape of the magnetoresistance depending on the structural and electronic properties of the semiconductor rather than on its magnetic properties. The absence of an anomalous Hall effect leads to the conclusion that ferromagnetic ordering is not the only factor necessary for the occurrence of asymmetric scattering in granular ferromagnetic materials.

► We report the presence of colossal magnetoresistance in a high TC ferromagnetic composite CdGeAs2: MnAs semiconductor.
► We examine the magnetoresistance and show that the effect correlates with the carrier mobility of the material.
► We model the magnetoresistance effect with the effective medium approximation method obtaining good agreement.