Nature of itineracy in CoV$_2$O$_4$: A first principles study

Abstract

Inspired by recent experiments, we have theoretically explored the nature of itineracy in CoV$_2$O$_4$ under pressure and investigated, using first principles density functional theory calculations, if it has any magnetic and orbital ordering. Our calculations indicate that there could be two possible routes to obtain the experimentally observed pressure induced metallicity in this system. One is the spin-orbit interaction coupled with Coulomb correlation which can take the system from a semiconducting state at ambient pressure to a metallic state under high pressure. The other mechanism, as indicated by our GGA+U calculations, is based on the presence of two types of electrons in the system: localized and itinerant. An effective Falicov-Kimball model could then possibly explain the observed insulator to metal transition. Comparison of the two scenarios with existing experimental observations leads us to believe that the second scenario offers a better explanation for the mechanism of insulator to metal transition in CoV$_2$O$_4$ under pressure.