Homogeneous versus composite Cd1-x-y Mnx Zny SnAs2 crystals: Magnetic interactions and transport properties.

We present the studies of structural, magnetic, and magnetotransport properties of Cd1-x-y Mnx Zny SnAs2 crystals with the average Mn contents x changing from 0.013 to 0.170 and Zn contents y varying from 0.002 to 0.051. Homogenous distribution of Mn ions is observed for the samples with x = 0.025. The presence of Mn As clusters in the studied alloy for x > 0.025 induces room-temperature ferromagnetism with the Curie temperature TC, with values around 325K. High crystal quality leads to high carrier mobility values observed for all of our samples, as high as 7100 cm²/(Vs) for x = 0.025 and y = 0.028. The Shubnikov-de Haas oscillations are observed at T = 50 K for all of our samples. The oscillations allowed the calculation of the effective mass m*, giving values of about 0.11-0.12me. The presence of magnetic impurities has a strong influence on the magnetoresistance of the alloy. For the samples with x = 0.076, the Shubnikov-de Haas oscillations are observed on the background of a strong linear positive magnetoresistance, present up to room temperature. The maximum values of the linear positive magnetoresistance are close to 200% for the sample with x = 0.170 and y = 0.002, at T = 1.5K. This positive magnetoresistance is related to the presence of Mn As clusters in the semiconductor lattice. [ABSTRACT FROM AUTHOR]