Interplay between magnetism and topology: large topological Hall effect in an antiferromagnetic topological insulator EuCuAs
Résumé
Magnetic interactions in combination with nontrivial band structures can give rise to several
exotic physical properties such as a large anomalous Hall effect, the anomalous Nernst effect
and the topological Hall effect (THE). Antiferromagnetic (AFM) materials exhibit THE due
to the presence of nontrivial spin structures. EuCuAs crystallizes in a hexagonal structure with
an AFM ground state (Néel temperature ~16 K). In this work, we observe a large topological
Hall resistivity of ~7.4 µΩ-cm at 13 K which is significantly higher than the giant topological
Hall effect of Gd2PdSi3 (~3 µΩ-cm). Neutron diffraction experiments reveal that the spins
form a transverse conical structure during the metamagnetic transition, resulting in the large
topological Hall effect. In addition, by controlling the magnetic ordering structure of EuCuAs
with an external magnetic field, several fascinating topological states such as Dirac and Weyl
semimetals have been revealed. These results suggest the possibility of spintronic devices
based on antiferromagnets with tailored noncoplanar spin configurations.
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