Effect of the 3d Electron Self-Interaction Correction on the Electronic and Magnetic Properties of CoGeN2, CrGeN2, MnSiN2, and MnGeN2

AbstractThe electronic structure has been calculated for new CoGeN2, CrGeN2, MnSiN2, and MnGeN2 crystals with a chalcopyrite structure in the antiferromagnetic (AFM) and ferromagnetic (FM) phases. It has been found that the AFM state is energetically favorable for all four materials. For the first time, the electronic properties of CoGeN2 and CrGeN2 have been studied using two exchange-correlation functionals, namely, GGA-PBE and PBE0. The second approach differs from the first one in that it includes the correction for the Coulomb self-interaction error (SIE) for strongly correlated 3d electrons. For example, without applying this correction, the bandgap in CoGeN2, MnSiN2, and MnGeN2 in the AFM phase is 0.11, 1.45, and 0.91 eV, and with inclusion of the SIE correction, it is 1.46, 3.47, and 1.37 eV, respectively. Without the SIE correction, CoGeN2 has metal properties for both spin orientations, and when the SIE correction is applied, it is a direct-gap semiconductor with a bandgap of 1.38 eV for spin up and 1.77 eV for spin down. The crystals under consideration are promising materials for magnetoelectronic applications.