Homogeneous Versus Composite Cd1-X-Ymnxznysnas2 Crystals: Magnetic Interactions And Transport Properties

We present the studies of structural, magnetic, and magnetotransport properties of Cd1-x-yMnxZnySnAs2 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 MnAs clusters in the studied alloy for x > 0.025 induces room-temperature ferromagnetism with the Curie temperature T-C, with values around 325 K. High crystal quality leads to high carrier mobility values observed for all of our samples, as high as 7100 cm(2)/(V s) 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 0.11-0.12m(e). 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 = 1.5 K. This positive magnetoresistance is related to the presence of MnAs clusters in the semiconductor lattice.