In this work, we synthesized single crystal of EuCd2As2, which exhibits A-type antiferromagnetic (AFM) order with in-plane spin orientation below TN = 9.5~K.Optical spectroscopy and transport measurements suggest its topological insulator (TI) nature with an insulating gap around 0.1eV. Remarkably, a dual topological Hall resistivity that exhibits same magnitude but opposite signs in the positive to negative and negative to positive magnetic field hysteresis branches emerges below 20~K. With magnetic force microscopy (MFM) images and numerical simulations, we attribute the dual topological Hall effect to the N\'{e}el-type skyrmions stabilized by the interactions between topological surface states and magnetism, and the sign reversal in different hysteresis branches indicates potential coexistence of skyrmions and antiskyrmions. Our work uncovers a unique two-dimensional (2D) magnetism on the surface of intrinsic AFM TI, providing a promising platform for novel topological quantum states and AFM spintronic applications.
@article{arxiv.2311.15835,
title = {Surface skyrmions and dual topological Hall effect in antiferromagnetic topological insulator EuCd$_2$As$_2$},
author = {Min Wu and R. Yang and Xiangde Zhu and Yixiong Ren and Ang Qian and Yongjie Xie and Changming Yue and Yong Nie and Xiang Yuan and Ning Wang and Daifeng Tu and Ding Li and Yuyan Han and Zhaosheng Wang and Yaomin Dai and Guolin Zheng and Jianhui Zhou and Wei Ning and Xianggang Qiu and Mingliang Tian},
journal= {arXiv preprint arXiv:2311.15835},
year = {2023}
}