Non-monotonic effect of the electronic transport and magnetic properties in a Sm-doped Sr2−x SmxIrO4system

Abstract

Sr2IrO4 has been shown to host a novel Mott spin-orbit insulating state with antiferromagnetic ordering. Here, the effects of Sm substitution at Sr-site on structural, electrical and magnetic properties are studied in Sr2IrO4. Sm-doped samples still retain the insulating behavior, but with the increase of Sm-doping concentration x, the resistivity firstly decreases for and then increases. We found that the increment of the Ir-O-Ir bond angle, combined with the modulation of the regularity of IrO6 octahedra, results in the non-monotonic variation of resistivity with x. On the other hand, there are two types of magnetic exchange interactions (i.e., Ir4+-O-Ir4+ and Sm3+-O-Ir4+) in the Sm-doped Sr2−xSmxIrO4 system. The antiferromagnetic component is greatly suppressed in the low concentration x and then an ascension emerges in the high concentration x, which is attributable to the competition between the weakened Ir4+-O-Ir4+ and enhanced Sm3+-O-Ir4+ exchange interactions.