Mott insulator-to-metal transition in yttrium-doped CaIrO3

TL;DR

This study investigates the insulator-to-metal transition in yttrium-doped CaIrO3, revealing a gradual transition contrasting with BaIrO3, and discusses implications for exotic ground states like superconductivity in post-perovskite Mott insulators.

Contribution

It provides new insights into the doping-induced transition in CaIrO3 and highlights differences from BaIrO3, challenging previous assumptions about ground states in these materials.

Findings

Yttrium doping induces metallic behavior in CaIrO3.

CaIrO3 does not necessarily have a j=1/2 ground state.

Both CaIrO3 and BaIrO3 exhibit magnetic character regardless of doping.

Abstract

We report on the study of insulator-to-metal transition in post-perovskite compound CaIrO3. It is discovered that a gradual chemical substitution of calcium by yttrium leads to the onset of strong metallic behavior in this compound. This observation is in stark contrast to BaIrO3, which preserves its Mott insulating behavior despite excess of charge carriers due to yttrium doping. Magnetic measurements reveal that both compounds tend to exhibit magnetic character irrespective of the chemical substitution of Ca or Ba. We analyze these unusual observations in light of recent researches that suggest that unlike BaIrO3, CaIrO3 does not necessarily possess j = 1/2 ground state due to structural distortion. The insulator-to-metal transition in CaIrO3 will spur new researches to explore more exotic ground state, including superconductivity, in post-perovskite Mott insulators.