Magnetism in Cr-doped ZnS: Density-functional theory studies

We investigated the magnetism and aggregation trends in cubic Zn1-xCrxS using the density-functional theory calculations.We demonstrate that all studied configurations show ground state half-metallic ferromagnetism (HMF); and Cr impurities are energetically favorable to planar cluster into delta-doping structures. The single-layer delta-doping structures of Zn0.75Cr0.25S and Zn0.875Cr0.125S show ferromagnetic stabilization energies (\Delta E_AF) of 0.551 and 0.561 eV/Cr-Cr pair, respectively. The half-layer delta-doping structure of Zn0.875Cr0.125S and double-layer delta-doping structure of Zn0.75Cr0.25S show \Delta E_AF of 0.394 and 0.166 eV/Cr-Cr pair, respectively. Furthermore, our studies indicate that the cubic ZnS/CrS heterostructure, one extreme situation of the delta-doping structure, also shows ground state HMF. The origin of HMF is discussed using a simple crystal field model. Finally, we anticipate the potential spintronics application of Zn1-xCrxS.