First-principles studies of the stability, structural, electronic, magnetic and optical properties of halogen atom doped marcasite FeS 2

The effects of halogen atom (F, Cl, Br or I) doping on the stability, structural, electronic, magnetic and optical properties of marcasite FeS 2 (m-FeS 2 ) are investigated through the first-principles calculations. The formation energies are relatively small under Fe-rich condition, indicating that it is feasible to implant halogen atom into m-FeS 2 . The ground state of halogen atom doped m-FeS 2 systems is magnetic due to the positive energy differences between non-spin-polarized and spin-polarized states. Phonon dispersion curves show that all doping systems are dynamically stable. The total magnetic moment of all doping systems is nearly 1 mu B , since replacing the S atom with a halogen atom introduces a non-bonding electron. Most of them come from Fe and S atoms, and only a small fraction come from the dopant. The simulation results show that F- and Br-doped m-FeS 2 systems are still semiconductors although the band gaps are reduced considerably, Cl-doped m-FeS 2 changes to a half-metal with half metallic band gap of 0.25 eV, while I-doped m-FeS 2 becomes a metal, making them potentially useful in spintronics. In addition, the halogen atom doped m-FeS 2 systems possess enhanced absorption coefficient and red-shifted absorption edge. So they are promising in optoelectronic device and solar energy harvesting.