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Recent observations of large anomalous Hall effects in the non-collinear antiferromagnets Mn₃X have opened new venues to study the effects of Berry curvature and their potential applications at room temperature. Our detailed experiments on the anomalous Hall and Nernst effects have clarified that large Berry curvature exists nearby the Fermi energy in the momentum space [1,2,3]. Besides, our measurements of ARPES, magnetoresistance, and their comparison with theory have provided strong evidence for the magnetic Weyl fermions in the ferro-ordered state of magnetic octupoles in Mn₃Sn [4]. In addition, we find that this Weyl antiferromagnet exhibits an anomalous type of spin Hall effect (magnetic spin Hall effect). If time permits, perspective for applications will be also discussed. This presentation is based on the collaboration with Takahiro Tomita, Tomoya Higo, Muhammad, Ikhlas, YoshiChika Otani, Motoi Kimata, Kouta Kondo, Kenta Kuroda, Takeshi Kondo, Shik Shin, Pallab Goswami, Hua Chen, Allan MacDonald, Ryotaro Arita, Michito Suzuki, Takashi Koretsune.

[1] S. Nakatsuji, N. Kiyohara and T. Higo, Nature 527, 212 (2015).
[2] N. Kiyohara, T. Tomita, S. Nakatsuji, Phys. Rev. Applied 5, 064009 (2016).
[3] M. Ikhlas, T. Tomita et al., Nature Physics 13, 1085 (2017).
[4] K. Kuroda, T. Tomita et al., Nature Materials 16, 1090 (2017).