Ba-substitution induced evolution of structural and magnetic properties of La2-xBaxCoIrO6 double perovskites

TL;DR

This study investigates how substituting Ba in La2-xBaxCoIrO6 double perovskites affects their structure and magnetic behavior, revealing a transition from ferrimagnetic to antiferromagnetic states linked to structural and electronic changes.

Contribution

It provides new insights into the relationship between Ba substitution, structural evolution, and magnetic properties in Ir-Co double perovskites.

Findings

Structural transition from monoclinic to triclinic with Ba doping

Ferrimagnetic behavior in x=0, 0.5, 0.75 compounds

Antiferromagnetic character in x=1.0 due to Ir magnetic moment quenching

Abstract

The Iridium-based oxides are the subject of great recent interest due to the non-conventional physics that may emerge from the strong spin-orbit coupling present in 5d ions. Here, we explore the coupling between Ir and Co in the La2-xBaxCoIrO6 perovskites (x = 0, 0.5, 0.75 and 1.0), where the structural, electronic, and magnetic properties of the series are investigated by means of x-ray powder diffraction and magnetometry. The system's crystal structure evolves from the monoclinic P2_1/n to the triclinic I-1 space group as the Ba concentration increases. Measurements of magnetization revealed ferrimagnetic behavior in x = 0, 0.5 and 0.75 compounds, possibly resulting from antiferromagnetic coupling between Co2+/3+ and Ir4+. In contrast, for x = 1.0 a clear collinear antiferromagnetic character is observed for the Co2+ ions, resulting from the quenching of the Ir5+ magnetic moment. The evolution of the magnetic properties of the series is discussed in terms of the structural and electronic changes, as well as the spin-orbit coupling in Ir.