Evolution of structural, electronic and magnetic properties upon Mg-doping in BaIrO3

Abstract

In last five years or so, correlated topological materials have attracted enormous attention. In these materials, the interplay between electronic correlations, spin-orbit coupling, and crystal field effect gives rise to unconventional “correlated topological phases,” such as spin-orbit assisted Mott insulator, Weyl semimetal, Axion insulator and a plethora of quantum spin liquids, that are a subject of significant contemporary interest.

In this work, we investigate a perovskite iridate, BaIrO3, which is a candidate correlated topological material. It shows a concomitant ferromagnetic and charge density wave (CDW) ordering at (Tc ∼ 180 K) along with an insulating ground state. BaIrO3 has a very sensitive structural and physical properties dependence on pressure. We synthesized Mg-doped samples: Ba1–x MgxIrO3 ( x = 0, 0.05, 0.1) and BaIr1–xMgxO3 (x = 0.05, 0.1, 0.15, 0.2, 0.3, 0.33) using the conventional solid-state reaction method. We obtained several single-phase samples either crystallizing with the 9R structure of BaIrO3 having a monoclinic symmetry, or with a hexagonal triple perovskite structure of Ba3MgIr2O9. The electronic and magnetic properties of single-phase samples has been studied. We show that up to 5% of Mg doping, the 9R structure remains stable, the electrical conductivity increases significantly and the magnitude of magnetic susceptibility decreases, but the magnetic ordering temperature remains unchanged, which suggests that the Ir-Ir exchange interaction remains nearly unchanged upon Mg doping but the ordered Ir moment weakens. The sample Ba3MgIr2O9, shows a paramagnetic susceptibility with no magnetic transition down to the lowest measurement temperature.