Enhanced magnetism and persistent insulating state in Mn doped Sr₂IrO₄

Abstract

The influences of Mn substitution at the Ir site of Sr2IrO4 are investigated via a comprehensive study of the variation of structural parameters, the transport and magnetic properties of the Sr2Ir1-xMnxO4 samples. The incorporation of Mn leads to an increase of the in-plane Ir-O-Ir bond angle, while it is not sufficient to drive the Mott-insulating state to a metallic state. Interestingly, we find a coexistence of Ir4+-O2--Ir4+ super-exchange interaction and Mn3+-O2--Mn4+ double exchange interaction in x≥0.06 samples. The Mn3+-O2--Mn4+ ferromagnetic domains are isolated by the Ir4+-O2--Ir4+ antiferromagnetic areas, leading to a severely localized electronic and magnetic states. The electron hopping between the localized states dominates the conductivity of the Sr2Ir1-xMnxO4 samples.