Two-Dimensional Surface Topological Nanolayers and Dirac Fermions in Single Crystals of the Diluted Magnetic Semiconductor (Cd1−x−yZnxMny)3As2 (x + y = 0.3)

Abstract

Features in the transverse magnetoresistance of single-crystalline diluted magnetic semiconductors of a (Cd1−x−yZnxMny)3As2 system with x + y = 0.3 have been found and analyzed in detail. Two groups of samples have been examined. The samples of the first group were thermally annealed for a long time, whereas the samples of the second group were not thermally annealed. The Shubnikov–de Haas (SdH) oscillations were observed for both groups of the samples within a 4.2 ÷ 30 K temperature range and under transverse magnetic field sweeping from 0 up to 11 T. The value of a phase shift, according to the SdH oscillations, was found to be a characteristic of the Berry phase existing in all the samples, except the unannealed sample with y = 0.08. Thickness of 2D surface topological nanolayers for all the samples was estimated. The thickness substantially depended on Mn concentration. The experimental dependence of reduced cyclotron mass on the Fermi wave vector, extracted from the SdH oscillations for the samples with different doping levels, is in satisfactory agreement with the predicted theoretical linear dependence. The existence of the Dirac fermions in all the samples studied (except the unannealed sample with y = 0.08) can be concluded from this result.