Non-coplanar spin textures with scalar spin chirality can generate effective magnetic field that deflects the motion of charge carriers, resulting in topological Hall effect (THE), a powerful probe of the ground state and low-energy excitations of correlated systems. However, spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy has not been considered in prior studies. Herein, we report direct evidence of universal spin chirality fluctuation by probing the THE above the transition temperatures in two different ferromagnetic ultra-thin films, SrRuO3 and V doped Sb2Te3. The temperature, magnetic field, thickness, and carrier type dependences of the THE signal, along with our Monte-Carlo simulations, unambiguously demonstrate that the spin chirality fluctuation is a universal phenomenon in two-dimensional Ising ferromagnets. Our discovery opens a new paradigm of exploring the spin chirality with topological Hall transport in two-dimensional magnets and beyond
@article{arxiv.1812.07005,
title = {Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy},
author = {Wenbo Wang and Matthew W. Daniels and Zhaoliang Liao and Yifan Zhao and Jun Wang and Gertjan Koster and Guus Rijnders and Cui-zu Chang and Di Xiao and Weida Wu},
journal= {arXiv preprint arXiv:1812.07005},
year = {2019}
}