Effect of hole doping on structural, electronic and magneto-transport properties of Sr2IrO4

Abstract

5d based oxide materials are subject of extensive research in recent times due to potential for novel electronic and magnetic phases. The iridium based oxides among them are extensively studied since novel physics in iridates is driven by enhanced spin orbital interaction (SOI) and reduced electronic interaction (U). Sr2IrO4 is single layered member of Ruddlesden Popper series is a spin orbital coupling driven insulator. To investigate the effect of charge doping in this material in this study we have attempted hole doping via Ru4+ (4d4) substitution on Ir4+ (5d5). Thus ruthenium doping introduces hole in the electronic band moreover, it also tune the SOI. We have synthesized the polycrystalline samples of Sr2Ir1-xRuxO4 with x = 0.0 0.1 and 0.2 phase pure samples were obtained with tetragonal structure and I4/acd symmetry. The temperature dependent resistivity is measured using four probe technique down in the temperature range 5 K -300 K. the resistivity decreased with doping however decrease in resistivity at room temperature is not significant but at low temperature the resistivity decreased by a factor of 10-3. The temperature dependent resistivity is fitted to thermal activated 2-dimensional Mott Variable range model. To understand electronic transport further field dependent magneto-resistance is also studied. Negative magneto-resistance (MR) has been observed at all samples at 5 K. The MR shows quadratic field dependence which implies a relevance of a quantum interference effect in this spin orbital coupled insulator.