Metal-metal transition in perovskitePbRuO3

Abstract

The high-pressure perovskite phase of ${\text{PbRuO}}_{3}$ is orthorhombic $Pbnm$ at room temperature and transforms in a first-order transition to $Imma$ below ${T}_{t}\ensuremath{\approx}90\text{ }\text{K}$; there is no long-range magnetic order above 1.5 K. We report a systematic study of the transport and magnetic properties versus temperature under high pressure of a single grain as well as the structural study under high pressure at room temperature. We found a metal-metal transition at 90 K in contrast to the semiconductor-insulator transition reported in the literature. We also compare the LT $Imma$ phase of ${\text{PbRuO}}_{3}$ with the $Imma$ phase found in the ${\text{Sr}}_{1\ensuremath{-}x}{\text{Ba}}_{x}{\text{RuO}}_{3}$ system. An important hybridization of the $\text{Pb-}6s$ and $\text{Ru-}4d$ orbitals is implicated.