Weida Wu1,Paul Sass1,Jinwoong Kim1,Jiaqiang Yan2,David Vanderbilt1
Rutgers University New Brunswick1,Oak Ridge National Laboratory2
Weida Wu1,Paul Sass1,Jinwoong Kim1,Jiaqiang Yan2,David Vanderbilt1
Rutgers University New Brunswick1,Oak Ridge National Laboratory2
Layered antiferromagnets with topological band structure are promising platforms to host many interesting topological phenomena [1,2]. Thus, it is imperative to visualize domains or domain walls in these topological antiferromagnets. Despite many decades’ efforts, it remains a grand challenge to visualize antiferromagnetic domains or domain walls in magnetic field [3]. Here I will present magnetic imaging of domain walls in antiferromagnetic topological insulator MnBi<sub>2</sub>Te<sub>4</sub> family using cryogenic magnetic force microscopy (MFM) [4]. Our MFM studies reveal enhanced magnetic susceptibility inside the domain walls due to the winding of the antiferromagnetic order parameter. In addition, our MFM data indicates the A-type antiferromagnetic order persists to the surface of MnBi<sub>2</sub>Te<sub>4</sub> [5], which shed new light on the mystery of gapless topological surface states observed by high resolution angle-resolved photoemission spectroscopy [6–8]. The robust A-type order is further corroborated by the surprising discovery of the long-sought surface spin-flop transitions<sub>. </sub> Our results pave the way for exploration of domain walls or surface magnetism in topological antiferromagnets using magnetic imaging [9,10].<br/><b>References:</b><br/>[1] Y. Deng, Y. Yu, M. Z. Shi, J. Wang, X. H. Chen, and Y. Zhang, <b>Science</b> 367, 895 (2020).<br/>[2] C. Liu, Y. Y. Wang, H. Li, Y. Wu, Y. Li, J. Li, K. He, Y. Xu, J. Zhang, and Y. Y. Wang, <b>Nat. Mater.</b> 19, 522 (2020).<br/>[3] S. W. Cheong, M. Fiebig, W. Wu, L. Chapon, and V. Kiryukhin, <b>Npj Quantum Mater.</b> 5, 1 (2020).<br/>[4] P. M. Sass, W. Ge, J. Yan, D. Obeysekera, J. J. Yang, and W. Wu, <b>Nano Lett.</b> 20, 2609 (2020).<br/>[5] P. M. Sass, J. Kim, D. Vanderbilt, J. Yan, and W. Wu, <b>Phys. Rev. Lett.</b> 125, 037201 (2020).<br/>[6] H. Li, S.-Y. Gao, S.-F. Duan, Y.-F. Xu, K.-J. Zhu, S.-J. Tian, W.-H. Fan, Z.-C. Rao, J.-R. Huang, J.-J. Li, Z.-T. Liu, W.-L. Liu, Y.-B. Huang, Y.-L. Li, Y. Liu, G.-B. Zhang, H.-C. Lei, Y.-G. Shi, W.-T. Zhang, H.-M. Weng, T. Qian, and H. Ding, <b>Phys. Rev. X</b> 9, 041039 (2019).<br/>[7] Y. J. Chen, L. X. Xu, J. H. Li, Y. W. Li, C. F. Zhang, H. Li, Y. Wu, A. J. Liang, C. Chen, S. W. Jung, C. Cacho, H. Y. Wang, Y. H. Mao, S. Liu, M. X. Wang, Y. F. Guo, Y. Xu, Z. K. Liu, L. X. Yang, and Y. L. Chen, <b>Phys. Rev. X</b> 9, 041040 (2019).<br/>[8] Y.-J. Hao, P. Liu, Y. Feng, X.-M. Ma, E. F. Schwier, M. Arita, S. Kumar, C. Hu, R. Lu, M. Zeng, Y. Wang, Z. Hao, H. Sun, K. Zhang, J. Mei, N. Ni, L. Wu, K. Shimada, C. Chen, Q. Liu, and C. Liu, <b>Phys. Rev. X</b> 9, 041038 (2019).<br/>[9] L. Šmejkal, Y. Mokrousov, B. Yan, and A. H. Macdonald, <b>Nat Phys</b> 14, 242 (2018).<br/>[10] V. Baltz, A. Manchon, M. Tsoi, T. Moriyama, T. Ono, and Y. Tserkovnyak, <b>Rev. Mod. Phys.</b> 90, 15005 (2018).