Holes' character and bond versus charge disproportionation in $s-p$ $AB{X}_3$ perovskites

Abstract

We use density functional theory methods to study the electronic structures of a series of $s-p$ cubic perovskites $AB{X}_3$: the experimentally available SrBiO${}_3$, BaBiO${}_3$, BaSbO${}_3$, CsTlF${}_3$, and CsTlCl${}_3$, as well as the hypothetical MgPO${}_3$, CaAsO${}_3$, SrSbO${}_3$, and RaMcO${}_3$. We use tight-binding modeling to calculate the interatomic hopping integrals $t_{sp\sigma }$ between the $B-s$ and $X-p$ atomic orbitals and charge-transfer energies $\Delta$, which are the two most important parameters that determine the low-energy electron and hole states of these systems. Our calculations elucidate several trends in $t_{sp\sigma }$ and $\Delta$ as one moves across the periodic table, such as the relativistic energy lowering of the $B-s$ orbital in heavy $B$ cations leading to strongly negative $\Delta$ values. Our results are discussed in connection with the general phase diagram for $s-p$ cubic perovskites proposed in Ref. 26, where the parent superconductors SrBiO${}_3$ and BaBiO${}_3$ are found to be in the regime of negative $\Delta$ and large $t_{sp\sigma }$. Here, we explore this further and search for new materials with similar parameters, which could lead to the discovery of new superconductors. Also, some considerations are offered regarding a possible relation between the physical properties of a given $s-p$ compound (such as its tendency to bond disproportionate and the maximal achievable superconducting transition temperature) and its electronic structure.

7 pages, 5 figures

Cited by in corpus (1)

• Discovery of Superconductivity in (Ba,K)SbO${}_3$