First-principles investigation of the electron-phonon interaction in OsN2:: Theoretical prediction of superconductivity mediated by N-N covalent bonds

A first- principles investigation of the electron- phonon interaction in the recently synthesized osmium dinitride ( OsN2 ) compound predicts that the material is a superconductor. Superconductivity in OsN2 would originate from the stretching of covalently bonded dinitrogen units embedded in the transition- metal matrix, thus adding dinitrides to the class of superconductors containing covalently bonded light elements. The dinitrogen vibrations are strongly coupled to the electronic states at the Fermi level and generate narrow peaks in the Eliashberg spectral function alpha F-2(omega). The total electron- phonon coupling of OsN2 is lambda= 0.37 and the estimated superconducting temperature T-c approximate to 1 K. We suggest that the superconducting temperature can be substantially increased by hole doping of the pristine compound and show that Tc increases to 4 K with a doping concentration of 0.25 holes/ OsN2 unit.