Magnetic anisotropy in strontium iridate (Sr2IrO4) is found to be large because of the strong spin-orbit interactions. In our work, we studied the in-plane magnetic anisotropy of Sr2IrO4 and traced the anisotropic exchange interactions between the isospins in the crystal. The magnetic-field-dependent torque τ(H) showed a prominent transition from the canted antiferromagnetic state to the weak ferromagnetic (WFM) state. A comprehensive analysis was conducted to examine the isotropic and anisotropic regimes and probe the easy magnetization axis along the ab plane. The angle-dependent torque τ(θ) revealed a deviation from the sinusoidal behavior, and small differences in hysteresis were observed around 0° and 90° in the low-magnetic-field regime. This indicates that the orientation of the easy axis of the FM component is along the b axis, where the antiferromagnetic to WFM spin-flop transition occurs. We compared the coefficients of the magnetic susceptibility tensors and captured the anisotropy of the material. The in-plane τ(θ) revealed a tendency toward isotropic behavior for fields with values above the field value of the WFM transition.
Bibliographical noteFunding Information:
The work at Kyungpook National University was supported by the Brain Korea (BK) and the National Research Funding (NRF) [Grants No. 2013R1A1A2063904 and No. 2016R1A2B4016656] by the Korean Government. The work at Yonsei University was supported by the NRF Grants No. NRF-2014S1A2A2028481, No. NRF-2015R1C1A1A02037744, No. NRF-2016R1C1B2013709, No. NRF-2017K2A9A2A08000278, and No. 2017R1A5A1014862 (SRC program: vdWMRC center) and partially by the Yonsei University Future-leading Research Initiative of 2014 (Grant No. 2016-22-0099). W.K. was supported by an NRF grant funded by the Korea Government (MSIP) (Grant No. 2015-001948). A portion of this work was supported by the National Research Council of Science & Technology (NST) (Grant No. CAP-16-01-KIST) by the Korean government (MSIP).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics