Giant Anomalous Hall Effect in quasi-2D Layered Antiferromagnet Co_1/3NbS₂

The discovery of the anomalous Hall effect (AHE) in bulk metallic antiferromagnets (AFMs) motivates the search of the same phenomenon in two-dimensional (2D) systems, where a quantized anomalous Hall conductance can in principle be observed. Here, we present experiments on the layered AFM Co_1/3NbS2, which exhibits AHE below the Néel temperature T_N=29 K in bulk crystals [1]. Our transport measurements on micro-fabricated devices reveal a pronounced anisotropy in the resistivity –indicative of the 2D character of the electronic properties– and show an extremely large AHE, with an anomalous Hall conductance of the order of e²/h per layer at low temperature [2]. The observed strong anisotropy of transport and the very large anomalous Hall conductance per layer make the properties of Co_1/3NbS₂ compatible with the presence of partially filled topologically non-trivial 2D bands originating from the magnetic superstructure of the antiferromagnetic state. Isolating atomically thin layers of this material and controlling their charge density may therefore provide a viable route to reveal the occurrence of the quantized AHE in a 2D AFM.


[1] N. J. Ghimire et al, Nat. Commun. 9, 3280 (2018).
[2] G. Tenasini et al, Phys. Rev. Research 2, 023051 (2020).