Tuning the structural, electronic and magneto-transport properties of spin-orbit Mott insulator Sr2IrO4

TL;DR

This study explores how annealing affects the structural, magnetic, and transport properties of Sr2IrO4, revealing disorder's significant role in its magnetic phases and conduction mechanisms.

Contribution

It provides new insights into how thermal treatment modifies the magnetic anisotropy, phase coexistence, and conduction mechanisms in Sr2IrO4, a spin-orbit Mott insulator.

Findings

Annealing reduces magnetic anisotropy and glassy phase extent.

Transport mechanisms shift from Arrhenius to VRH models with temperature.

Annealed sample shows higher negative magneto resistance across temperatures.

Abstract

We investigate the tunability of the structural, electronic and magneto transport properties of polycrystalline Sr2IrO4 sample. The extent of bifurcation of the magnetisation curves during the field cooled and zero field cooled cycles establishes that the magnetic anisotropy in the as-prepared sample is more as compared to the vacuum annealed one. Based on the behaviours of the structural parameters and the magnetic studies, our results show that the canted AFM structure is stabilised in a larger temperature range in the case of the annealed sample as compared to the as prepared one. At low temperatures, for both the samples, a phase, possibly of glassy nature competes with the canted AFM phase. The temperature extent to which both these phases co-exist for the as-prepared and the annealed one is around 115K an 70K, respectively. The transport studies reveal that for both the samples, in the high temperature region of study, the conduction mechanism is governed by the Arrhenius model. In the intermediate temperature range, variable range hopping(VRH) and Arrhenius models govern the transport in the as-prepared and the annealed one, respectively. At low temperatures, the conduction mechanism occurs through Efros-Shklovskii-VRH and VRH mechanisms for the as-prepared and the annealed samples, respectively. The magneto resistance measurements indicate higher negative magneto resistance in the annealed sample at all temperatures. The field dependence of magneto resistance at 10K suggests a co-existing glassy magnetic phase along with the canted antiferromagnetic structure in the as prepared sample and a suppression of this glassy magnetic phase in the annealed sample. The combined analyses of all the results highlight the role of disorder for the magnetic and trasnport properties of this compound.