Multipole control of large electric and magnetic responses in Weyl antiferromagnets

Antiferromagnets have attracted recent interest for designing next generation high-density and ultrafast spintronics devices because they produce no stray fields and have much faster dynamics. Here we present novel functionality found in chiral antiferromagnets with vanishingly small magnetization, namely, topological Weyl magnets that can be easily controlled by magnetic field, produce large responses, and thus could be useful for applications. In particular, we discuss frustrated antiferromagnets, Mn₃X (X =Sn and Ge) as the examples of a magnetic Weyl semimetal or Weyl magnet [1,2,3]. We show that the cluster multipole order on the kagome lattice of Mn moments can be easily controlled and allows the system to exhibit a variety of new functions at room temperature that have never been seen in antiferromagnetic metals. These include the large anomalous Hall and Nernst effects [1,2,4], large magnetic optical Kerr effect [5] and a novel type of spin Hall effect (magnetic spin Hall effect) [6]. Finally, we show that they should be significantly useful for designing antiferromagnetic spintronics [7], and energy harvesting technology for magnets [8]. This presentation is based on the collaboration with T Tomita, T Higo, M Ikhlas, Y Otani, M Kimata, K Kondo, K Kuroda, T Kondo, S Shin, P Goswami, H Chen, A MacDonald, R Arita, M Suzuki, T Koretsune.


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