Anomalous Hall resistivity and possible topological Hall effect in the EuAl4 antiferromagnet

We report the observation of anomalous Hall resistivity in single crystals of EuAl4, a centrosymmetric tetragonal compound, which exhibits coexisting antiferromagnetic (AFM) and charge-density-wave (CDW) orders with onset at TN∼15.6K and TCDW∼140K, respectively. In the AFM state, when the magnetic field is applied along the c-axis direction, EuAl4 undergoes a series of metamagnetic transitions. Within this field range, we observe a clear humplike anomaly in the Hall resistivity, representing part of the anomalous Hall resistivity. By considering different scenarios, we conclude that such a humplike feature is most likely a manifestation of the topological Hall effect, normally occurring in noncentrosymmetric materials known to host nontrivial topological spin textures. In view of this, EuAl4 would represent a rare case where the topological Hall effect not only arises in a centrosymmetric structure, but it also coexists with CDW order.