Search for New Half-Metallic Ferromagnets in Quaternary Diamond-Like Compounds I-II2-III-VI4 and I2-II-IV-VI4 (I = Cu; II = Mn, Fe, Co; III = In; IV = Ge, Sn; VI = S, Se, Te)

The structural, electronic, and magnetic properties I-II2-III-VI4 and I-2-II-IV-VI4 are investigated firstly by using the first-principles calculations. The investigation was done using the ab initio full-potential linearized augmented plane wave (FPLAPW) method where the exchange-correlation potential was calculated with the frame of GGA and GGA+U. The theoretically predicted lattice parameters for I-II2-III-VI4 and I-2-II-IV-VI4 alloys are in good agreement with existing experimental measurements. The possibility of half-metallic ferromagnetism in I-II2-III-VI4 and I-2-II-IV-VI4 (I = Cu; II = Mn, Fe, Co; III = In; IV = Ge, Sn; VI = S, Se, Te) was analyzed by electronic band structure and density of states calculations. We found that Cu2CoGeS4, Cu2FeGeS4, Cu2FeSnS4, and CuMn2InSe4 compounds exhibit a complete half-metallic characteristic with a total spin moment of 3.00, 4.00, 4.00, and 10.00 mu (B) and direct band gap of (Eg a dagger = 0.63 eV), (Eg a dagger = 0.90 eV), (Eg a dagger = 0.31 eV), and (Eg a dagger" = 1.10 eV), respectively. These results may be of interest for spintronic applications.