Absence of Weyl nodes in EuCd 2 As 2 revealed by the carrier density dependence of the anomalous Hall effect

The antiferromagnetic layered compound EuCd2As2 is widely considered a leading candidate of ideal Weyl semimetals, featuring a single pair of Weyl nodes in its field-induced ferromagnetic state. Nevertheless, this view was recently challenged by an optical spectroscopy study, which suggested that it is a magnetic semiconductor. In this study, we successfully synthesized highly insulating EuCd2As2 crystals with carrier density reaching as low as 2 x 1015 cm-3. The magnetotransport measurements revealed a progressive decrease of the anomalous Hall conductivity (AHC) by several orders of magnitude as the carrier density decreases. This behavior contradicts what is expected from the intrinsic AHC generated by the Weyl points, which is independent of carrier density as the Fermi level approaches the charge neutrality point. In contrast, the scaling relationship between AHC and longitudinal conductivity aligns with the characteristics of variable-range hopping insulators. Our results suggest that EuCd2As2 is a magnetic semiconductor rather than a topological Weyl semimetal.