The marriage of magnetism and topology in quantum materials leads to many fascinating phenomena. Examples include quantum anomalous Hall effect, axion insulator states, topological superconductivity [1-3], where topological properties couple to magnetic domains or domain walls. The coupling also enable control and manipulate these topological phenomena with magnetic field. Therefore, it is imperative to visualize these mesoscopic magnetic textures in these topological materials. In this talk, I will present our recent efforts on magnetic imaging of domains or domain walls in single crystals, thin films and heterostructures of (antiferro-)magnetic topological insulators using magnetic force microscopy (MFM) [1–6]. In addition, our MFM studies reveal long-sought surface metamagnetic transitions in MnBi2Te4 family [6,7]. Our results pave the way for a further exploration of topological phenomena controlled by domains, domain walls or surface magnetism in quantum materials.
*This work is supported by DOE BES under Award No. DE-SC0018153.
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Publication:[1] W. Wang, Y. Ou, C. Liu, Y. Wang, K. He, Q.-K. Xue, and W. Wu, Nat. Phys. 14, 791 (2018). [2] D. Xiao, J. Jiang, J. H. Shin, W. Wang, F. Wang, Y. F. Zhao, C. Liu, W. Wu, M. H. W. Chan, N. Samarth, and C. Z. Chang, Phys. Rev. Lett. 120, 56801 (2018). [3] H. Yi, et al, Science, in press, (2023). [4] P. M. Sass, W. Ge, J. Yan, D. Obeysekera, J. J. Yang, and W. Wu, Nano Lett. 20, 2609 (2020). [5] W. Ge, P. M. Sass, J. Yan, S. H. Lee, Z. Mao, and W. Wu, Phys. Rev. B 103, 134403 (2021). [6] P. M. Sass, J. Kim, D. Vanderbilt, J. Yan, and W. Wu, Phys. Rev. Lett. 125, 037201 (2020). [7] W. Ge, J. Kim, Y. Chan, D. Vanderbilt, J. Yan, and W. Wu, Phys. Rev. Lett. 129, 107204 (2022).
