ELECTRICAL AND MAGNETIC-PROPERTIES OF THE SEMIMAGNETIC SEMICONDUCTORSHG1-XMNXTE1-YSEY

The results of experimental studies of single crystals of the solid so lutions Hg1-xMnxTe1-ySey with y = 0.01 and x = 0.03, 0.05, 0.14, and 0 .30 are presented. The magnetic properties (in the temperature range 3 00-4.2 K), the temperature dependences of the resistance from 300 to 4 .2 K, and the magnetoresistance at 4.2 K in magnetic fields of up to 3 5 T were studied. Transitions to a spin-glass state were observed for the last two compositions. The characteristic magnetic properties are explained in terms of the appearance of clusters of the type Mn-Te-Mn- Te, Mn-Se-Mn-Se, and Mn-Te-Mn-Se and in terms of the antiferromagnetic interaction of Mn atoms within clusters. At 4.2 K a giant negative ma gnetoresistance is observed; it is associated with the change in the o verlapping of the wave functions of accepters in a magnetic field. A c hange in the sign of the Hall coefficient with increasing temperature and its complex behavior in a magnetic field are explained in terms of the existence of three groups of carriers - electrons and two types o f holes, for which the temperature dependences of the mobilities were obtained. (C) 1995 American Institute of Physics.