Effect of self-organized quantum structures on spinglass and metal-insulator transition in CdMnTe single crystals

Vapour phase grown Cd1−xMnxTe crystals with x=0.2,0.3,0.4 and 0.5 were found to contain self-organized quantum structures as revealed by SEM micrographs. ac Susceptibility measurements were carried out in the temperature range 14-300 K at 313 Hz. Both the real and imaginary parts of susceptibility showed formation of spinglass phase at low temperatures. Dark and photo current studies in the temperature range 125-450 K indicated metal-semiconductor transitions. Further, photo excitation seemed to enhance the metal-semiconductor phase transition temperature. Both the spinglass formation and metal-semiconductor transition temperatures observed in the present CdMnTe samples were much higher than the earlier reported values and are attributed to the presence of self-organized microstructures.