Magnetism of insulator Sr2IrO4 with strong spin-orbit coupling

The magnetic properties of polycrystalline sample Sr2IrO4 have been investigated by the magnetization, electron magnetic resonance (EMR), the infrared (IR) and Raman spectra measurements. Our experimental results indicate that the magnetism is determined by the effective total angular moment J(eff) = 1/2 instead of the spin with S = 1/2. The temperature dependence of macromagnetic moment, resonance field of EMR line, A(2u) mode of IR and A(1g) mode of Raman spectra exhibit interesting behavior at about 40 K. Due to the Dzyaloshinskii-Moriya interaction, the magnetic order is canted, and the ferromagnetic component decreases with decreasing temperature. These complex magnetic behaviors in the system are attributed to the change of Ir-O-Ir bond angle with cooling, while the variation of bond angle is observed through the IR and Raman spectra. (c) 2013 Elsevier B.V. All rights reserved.