TRANSFER HYPERFINE INTERACTION IN CD1-XMNXTE STUDIED BY NMR

NMR measurements of Te-125 and Cd-113 have been performed on a series of samples of Cd1-xMn(x)Te (x = 0.01, 0.015, 0.02, 0.029, 0.055). The nuclear spin-lattice relaxation rates of the two nuclei are enhanced by two orders of magnitude compared to the relaxation rates of the same nuclei in the non-magnetic II-VI semiconductor alloys. Well-resolved Cd-113 and Te-125 spectra were obtained using the magic-angle-spinning technique. The line shifts are temperature dependent and follow the Curie-Weiss law, indicating that the predominant interaction responsible for the NMR behavior is the transfer hyperfine interaction of the Mn2+ ion with the Cd or Te nuclei. All the lines in the Te spectra and all but two of the lines in the Cd spectra are shifted to higher frequencies with reference to the NMR line in CdTe. A full spectral assignment has been obtained based on two assumptions: (i) the Mn ions are randomly distributed in the lattice, and (ii) the transfer hyperfine interaction that causes the line shifts depends on the number of bonds between the Mn ion and the Cd (or Te) ion. According to the spectral assignment, the spin density transferred to the Cd sites in the lattice decreases tenfold from one Cd shell to the next.