W. Lubczyński

Anisotropy of the Shubnikov-de Haas effect in Cd3-x-yZnxMnyAs2

Abstract Shubnikov-de Haas effect has been studied in single crystal samples of the tetragonal diluted magnetic semiconductor Cd 2.585 Zn 0.4 Mn 0.015 As 2 for different orientations of magnetic field with respect to the crystallographic axes. The observed angular dependences of the oscillation period are well described by an ellipsoidal Fermi surface given by the Bodnar model of the band structure. To calculate the anisotropy of the electron effective g -factor, a model based on a Hamiltonian matrix, found for the case of an arbitrary direction of the magnetic field, has been used. By fitting the theoretical model to the experimental data, the values of the exchange interaction constants have been evaluated.

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.

Spin Dependent Scattering in (Cd1−x−yZnxMny)3As2 from the Shubnikov-de Haas Waveshape Analysis

The study of the Shubnikov-de Haas effect (SdH) in (Cd1− x−yZnxMnY)3As2 with x=0.03 and y=0.006 has been performed in high magnetic fields up to 25 T. From the detailed waveshape analysis of SdH oscillations, the contribution of spin dependent scattering of the conduction electrons on magnetic ions to the total relaxation time has been determined and compared with the theoretical prediction derived for this purpose.