Magnetic properties of ( Cd1− x− yZnyMnx) 3As2

Abstract

We have studied the specific heat, magnetization and susceptibility of the tetragonal diluted magnetic semiconductor (DMS) ( Cd 1− x− y Zn y Mnx x ) 3 As 2 (CZMA) with various compositions in dc magnetic fields up to 17 T and in the temperatu range 1.3−300 K. The complicated crystal structure of CZMA has inspired us to generalize the pair approximation, widely used in analysis of the magnetic behaviour of II-VI DMSs, for an arbitrary structure. The resulting model, which may be called the generalized pair approximation (GPA), has been subsequently applied to interpret the results of our magnetic measurements performed on CZMA. Based on theoretical analyses concerning the Mn-Mn interaction in DMSs, which show that the dominant roles in this process are played by superexchange and the Bloembergen-Rowland exchange, we have obtained satisfactory agreement between our approach and experiment by using the analytical formulae with only two adjustable parameters, i.e. the first nearest-neighbour exchange constants for both mechanisms, which appear to be strongly dependent on Zn content.