Chiral fluctuation driven topological Hall effect in two-dimensional ferromagnets*

Topological Hall effect (THE) is a real space Berry phase phenomenon originated from the non-coplanar spin texture[1]. Recently THE has been associated with the formation of skyrmions in chiral magnets[2][3]. Although chiral fluctuation driven topological charges have been predicted in chiral magnets, the resultant THE has not been observed yet[4]. Herein, we report a surprising observation of THE around ferromagnetic transition temperature T_C in the ferromagnetic SrRuO₃ thin films. The temperature, magnetic field, and thickness dependence of THE are in good agreement with our Monte-Carlo simulations, which provides compelling evidence of the emergence of net topological charges due to chiral fluctuation.

References:
[1] Y. Taguchi, Y. Oohara, H. Yoshizawa, N. Nagaosa, Y. Tokura, Science 291, 2573 (2001).
[2] A. Neubauer, et al., Phys. Rev. Lett. 102, 186602 (2009).
[3] N. Kanazawa, et al., Phys. Rev. Lett. 106, 156603 (2011).
[4] W.-T. Hou, J.-X. Yu, M. Daly, J. Zang, Phys. Rev. B 96, 140403(R) (2017).