Ferromagnetic properties of (Zn,Mn,Ge)P2 layers on diamagnetic ZnGeP2 single crystal substrates

Magnetic properties of a volumetric area in the heterosystem of ferromagnetic (Zn,Mn,Ge)P2--diamagnetic ZnGeP2 have been studied. The formation of the ferromagnetic layer on the surface of ZnGeP2 crystal accompanies with Mn-diffusion inward the crystal bulk. Manganese penetrates deep into the crystal and occupies Zn sites in the chalcopyrite lattice. Mn2+ ions are paramagnetic active in the sites and show five EPR sets of equidistant peaks. Photo-EPR spectra discover optically active behavior of point defects likely VP in ZnGeP2 and (Zn,Mn,Ge)P2 at low temperatures. The defects have a tetrahedral symmetry and are surrounded with four phosphorus atoms. The measurement of magnetization M versus temperature T at zero-field-cooling results in Curie temperature of TC=318 K. The low temperature M(T) dependence displays uneven feature ascribed to competitive the second magnetic sublattice in (Zn,Mn,Ge)P2 due to Mn ions in a different valence state. 14 refs.