Self-doping induced orbital-selective Mott transition in Hg2Ru2O7

Pyrochlore oxides are fascinating systems where strong multiorbital correlations in concert with geometrical frustration give rise to unanticipated physical properties. The detailed mechanism of the insulator-metal transitions (IMTs) underpinning these phenomena is, however, ill understood in general. Motivated thereby, we study the IMT in the pyrochlore Hg2Ru2O7 using local-density approximation plus dynamical mean-field theory. In contrast to the well-known examples of Mott transitions in transition metal oxide, we show that in the negative charge-transfer situation characteristic of Hg2Ru2O7, self-doping plays a crucial role in the emergence of an orbital-selective IMT. We argue that this mechanism has broader relevance to other correlated pyrochlore oxides.