Investigating the intrinsic anomalous Hall effect in MnPt3 topological semimetal

Abstract

The cubic Cu${}_3$Au-type $X$Pt${}_3$ family ($X$ = V, Cr, and Mn) is a topological semimetal characterized by anti-crossing gapped nodal lines near the Fermi level, which give rise to significant Berry curvatures and thus to the anomalous Hall effect (AHE). Among the three members, CrPt${}_3$ has been experimentally verified to exhibit a large anomalous Hall conductivity (AHC), while its counterparts MnPt${}_3$ and VPt${}_3$ remain largely unexplored. Here, a series of MnPt${}_3$ thin films with varying thicknesses (20--70 nm) was epitaxially grown on the MgO substrates using magnetron sputtering and was systematically investigated by magnetization, electrical resistivity, and Hall resistivity measurements. MnPt${}_3$ films undergo a ferromagnetic transition at a Curie temperature $T_{\mathrm{C}}$, which increases as the film thickness increases, reaching $\sim$ 344 K for the 70-nm-thick film. All the anomalous Hall transport properties of MnPt${}_3$ films, including the resistivity, conductivity, and angle, exhibit a strong correlation with their magnetic properties. The scaling analysis suggests that the intrinsic Berry-curvature mechanism dominates the observed AHE, while the extrinsic contributions are much smaller. The intrinsic AHC increases as the film thickness increases, while the extrinsic AHC is thickness-independent. Such an enhanced intrinsic AHC in the MnPt${}_3$ films is most likely attributed to the strain effect, implying that it serves as an effective method to tune the electronic band topology in the $X$Pt${}_3$ topological semimetal.

8 pages, 5 figures; accepted by Phys. Rev. B