MAGNETIC-INTERACTIONS IN DILUTED SYSTEMS FROM LOW-TEMPERATURE MAGNETIZATION STEPS

In diluted magnetic systems, field induced level crossings can change the magnetic moment of the ground state of spin clusters. At low enoug h temperatures this will lead to steps in the magnetization vs. field curves, from which a variety of information can be extracted. Using a sensitive magnetometer operating below 50 mK, we have studied: 1) the dominant antiferromagnetic exchange constant between Eu++ ions in IV-V I Diluted Magnetic Semiconductors (DMSs); 2) distant-neighbor exchange constants in II-VI DMSs; 3) crystal field parameters for Co++ ions in CdS and CdSe; 4) the distribution of Jahn-Teller distortions for Cr+ ions in ZnTe; and 5) inequivalent nearest neighbors exchange constant s in Cd1-xMnxSe. Selected results and a description of the apparatus a re presented.