Band Jahn-Teller Instability and Formation of Valence Bond Solid in a Mixed-Valent Spinel Oxide LiRh2O4

Abstract

We have synthesized a new spinel oxide LiRh2O4 with a mixed-valent configuration of Rh3+ and Rh4+. At room temperature it is a paramagnetic metal, but on cooling, a metal-insulator transition occurs and a valence bond solid state is formed below 170 K. We argue that the formation of valence bond solid is promoted by a band Jahn-Teller transition at 230 K and the resultant confinement of t2g holes within the xy band. The band Jahn-Teller instability is also responsible for the observed enhanced thermoelectric power in the orbital disordered phase above 230 K.

7 pages, 4 figures

References in corpus (2)

• "Pudding mold" band drives large thermopower in Na${}_x$CoO${}_2$
• Magnetic transition and orbital degrees of freedom in vanadium spinels

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