First Principle Study on the Magnetic and Electric Properties of Wurtzite Cr-phosphides and Cr-sulphides: Several Half-metallic Ferromagnets

The geometrical structures of wurtzite CrX (X=As, Sb, O, Se, and Te) were optimized, then their electric and magnetic properties were investigated by the ˉrst-principle calculations within the generalized gradient approximation for the exchange-correlation functional based on the density functional theory. These Cr-phosphides and Cr-sulphides were predicted to be half-metallic ferromagnets whose spin-polarization at the Fermi level is absolutely 100%.The molecular magnetic moments of Cr-phosphides and Cr-sulphides are 3.00 and 4.00 μB, which arise mainly from Cr-ions, respectively. There is ferromagnetic coupling in both Cr-phosphides and Cr-sulphides. The Curie temperatures of Cr-sulphides and Cr-phosphides are high. The electronic structures of Cr-ions are a²_1g↑↓t⁴_1u↑↓t¹_1u e²_g↑in Cr-phosphides and a²_1g↑↓t⁴_1u↑↓t¹_1u↑t³_2g↑in Cr-sulphides, respectively.