Anomalous Hall effect in HfTe₅ thin flakes

Van der Waals (vdW) type topological materials provide a unique platform for studying what the role of dimensionality effect is played on topological properties. Topological pentatellurides, with a vdW layered structure, have been shown to display a lot of intriguing quantum transport properties in the bulk form. Here we report on the magnetotransport properties of HfTe₅ thin flakes We fabricate the HfTe₅ thin flake devices, with a thickness ranging from 90 nm to 280 nm, inside an argon filled glove-box and cap the samples with hBN to ensure that the sample quality is pristine. We observe the anomalous Hall effect (AHE) that evolves with temperature and sample thickness in all of the thin flake devices. The anomalous Hall effect remains persistent in the presence of high magnetic fields. We have tried different models to fit longitudinal and Hall conductivity. The AHE we have observed is likely due to a nontrivial Berry curvature caused by Zeeman spin splitting of the massive Dirac bands. Our magnetotransport results give new insight into how the Zeeman effect influences the topological band in HfTe₅.