Possible high-pressure orbital quantum criticality and an emergent resistive phase in PbRuO3

The orbital ordering transition in the metallic perovskite PbRuO3 is suppressed from 90 K at ambient pressure towards zero temperature at 50 kbar, where non-Fermi liquid resistivity with a temperature exponent n = 1.6 is observed. This evidences a possible quantum critical point brought about by orbital fluctuations, rather than spin fluctuations as observed in Sr3Ru2O7 and heavy fermion conductors. An anomalous increase of resistivity is observed at pressures above ∼100 kbar, and a transition to a more resistive, possibly semiconducting, phase is observed at 300 kbar and ambient temperature. © 2013 American Physical Society.