Interaction between 3d-, 4d- and 5d-electron in Sr2Ir1−x(Ru,Ti)xO4

• We study the substituting effect of Ti4+ and Ru4+ for Ir4+ in Sr2IrO4.
• We confirm that the magnetism of Sr2Ir1−x(Ru,Ti)xO4 is determined by J.
• We observe the percolation phenomenon in Sr2Ir1−xRuxO4 when 0.31≤x≤0.60.31≤x≤0.6.
• The increase of resistivity in Sr2Ir1−xTixO4 is illustrated by optical measurement.

The effect of substituting 3d-nonmagnetic Ti4+ and 4d-magnetic Ru4+ for 5d-magnetic Ir4+ in Sr2IrO4 polycrystals has been studied. The magnetic transition temperature TN decreases with Ru doping, while TN is almost unchanged with Ti doping. This phenomenon indicates that there is super-exchange coupling between Ir4+ and Ru4+, which is weaker than that of Ir–O–Ir, while there is no interaction between Ir4+ and Ti4+. The resistivity of Sr2Ir1−xRuxO4 decreases with increasing x   due to the introduction of holes upon Ru doping, and the ρ–Tρ–T relation presents the percolation phenomenon in 0.31 ≤x≤≤x≤ 0.6 range. On the contrary, the resistivity of Sr2Ir1−xTixO4 increases with x. The increase of ρ is attributed to the scattering of additional vibration modes of Sr2TiO4 in which are measured by IR spectra.