Self-Doping Induced Orbital-Selective Mott Transition in Hg2Ru2O7

TL;DR

This paper investigates the insulator-metal transition in Hg2Ru2O7, revealing that self-doping induces an orbital-selective Mott transition driven by strong correlations and geometrical frustration.

Contribution

It demonstrates that self-doping is a key mechanism for the orbital-selective IMT in Hg2Ru2O7, expanding understanding of phase transitions in pyrochlore oxides.

Findings

Self-doping drives the orbital-selective IMT in Hg2Ru2O7.

The mechanism differs from traditional Mott transitions in transition metal oxides.

Broader relevance to other correlated pyrochlore oxides is suggested.

Abstract

Pyrochlore oxides are fascinating systems where strong, multi-orbital correlations in concert with geometrical frustration give rise to unanticipated physical properties. The detailed mechanism of the insulator-metal transitions (IMT) underpinning these phenomena is, however, ill-understood in general. Motivated thereby, we study the IMT in the pyrochlore ${\rm Hg_{2}Ru_{2}O_{7}}$ using LDA+DMFT. In contrast to the well-known examples of Mott transitions in TMO, we show that, in the negative charge-transfer situation characteristic of \hg, 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.