Chromium trihalides are layered and exfoliable semiconductors and exhibit unusual magnetic properties with a surprising temperature dependence of the magnetization. By analyzing the evolution of the magnetocrystalline anisotropy with temperature in chromium iodide CrI3, we find it strongly changes from Ku=300±50kJ/m3 at 5K to Ku=43±7kJ/m3 at 60K, close to the Curie temperature. We draw a direct comparison to CrBr3, which serves as a reference, and where we find results consistent with literature. In particular, we show that the anisotropy change in the iodide compound is more than 3 times larger than in the bromide. We analyze this temperature dependence using a classical model, showing that the anisotropy constant scales with the magnetization at any given temperature below the Curie temperature, indicating that the temperature dependence can be explained by a dominant uniaxial anisotropy where this scaling results from local spin clusters having thermally induced magnetization directions that deviate from the overall magnetization.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Prof. Dr. Gerhard Jakob, Prof. Dr. Hartmut Zabel, and Prof. Dr. Hans-Joachim Elmers for stimulating and helpful discussions. The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST). The work was further funded by the DFG (SFB TRR 173 Spin+X), and N.R. gratefully acknowledges the MAINZ Graduate School of Excellence (DFG GSC/266) as well as the Carl Zeiss Stiftung. D.W. and B.V.L. are grateful for support from the Max Planck Society, the University of Munich (LMU), the Cluster of Excellence Nanosystems Initiative Munich (NIM), and the Center of Nanoscience (CeNS).