Pseudogap and electron localization in the 4d shell of NbO2 bulk crystal

We present a detailed study of correlation-induced electronic reconstruction in ${\mathrm{NbO}}_{2}$ bulk crystal. Using density functional plus dynamical mean-field theory $(\mathrm{DFT}+\mathrm{DMFT})$, we show the importance of multiorbital Coulomb interactions in concert with first-principles band structure calculations for a consistent understanding of emergent pseudogap and incipient Mott localization in ${\mathrm{NbO}}_{2}$. We explain the pseudogapped incoherent metal to a Mott-localization-like transition seen in experiment. We trace its origin to changes in orbital polarization, itself renormalized from its DFT value by sizable multiorbital electron correlations. Our results should be of interest for future studies on electronic switching in Mott memristors for neuromorphic computing devices.