Modulation Of Properties By Sn-doping And IrO₂ Layers In J_eff=1/2 Antiferromagnet Sr₂IrO₄

Multi-freedom coupling in quantum materials can generate a series of novel physical properties and is one of the focus of condensed matter physics research.Two subjects were carried out in this paper based on the Sr₂IrO₄ single crystal.The first one is doping Sn O₂ in Sr₂IrO₄ to explore the impacts on physical properties of Sr₂IrO₄,where the Ir ions are replaced by the non-magnetic Sn ions.The second one is synthesizing eutectic crystals with different proportions of Sr₂IrO₄ and Sr₃Ir₂O₇ structural single crystals to modulate the number of IrO₂ layers,which is to understand the intralayer and interlayer coupling mechanisms in Sr₂IrO₄.The related results are as follows:(1)The physical properties of the Sr₂Ir_(1-x)Sn_xO₄(x?0.08) single crystals were studied in detail.The experiment results show that the lattice constant a and the Ir-O-Ir bond angle are enlarged as increasing the Sn content,but c is reduced.As for magnetism,T_Nis dropped and the magnetic field induced spin flop is disappeared by introducing the nonmagnetic Sn ions,indicating the diluted AFM interactions.In addition,all the single crystals exhibit insulator properties no matter in the ab-plane or along the c-axis.The resistivity is first reduced and then increased as increasing x.The fitted results illustrate from the high temperature zone(300K-90K)to the low temperature zone(<50K),the electronic transport behavior transitions from the thermal activation model whose energy increased,to the Mott-VRH model,whose energy is first reduced then increased.In terms of current effects,the resistivity of all components decreases with a increase in current.The larger x,the greater the resistance drop.(2)The Sr_n+1Ir_nO_3n+1(1?n?2) eutectic system was synthesized using flux-method in the basis of the growth technique of Sr₂IrO₄ and Sr₃Ir₂O₇ single crystal.The magnetic measurement shows that the interlayer AFM interactions are enhanced by increasing the IrO₂ layers,resulting in an increase of T_Nin Sr₂IrO₄.The magnetic resistance effect of Sr₂IrO₄ is impaired as increasing the number of IrO₂ layers.