Antiferromagnetic Weyl semimetals with spin chirality offer excellent platforms to address the Berry phase physics, which manifests prominently in several of their electro-optical and electromagnetic responses including as a large anomalous Hall effect (AHE) and spin Hall conductivity. The ${\mathrm{Mn}}_3\mathrm{Sn}$ and ${\mathrm{Mn}}_3\mathrm{Ge}$ compounds, where the Mn spins arrange in a kagome lattice, are examples of this class of materials. Here, we report on measurements of magnetotransport in $c$-axis textured ${\mathrm{Mn}}_3\mathrm{Sn}$ thin films grown on the [111] plane of single-crystal MgO by dc magnetron sputtering. At room temperature, these films display a weak uncompensated magnetic moment of $\approx 0.12{\mu }_{\mathrm{B}}/\mathrm{f}.\mathrm{u}.$ in the basal plane and a longitudinal resistivity (${\rho }_{xx}$) $\approx 3.8\mu \mathrm{\Omega }\mathrm{m}$, which matches well with the bulk value. A residual resistivity ratio $[{\rho }_{xx}\left(300K\right)/{\rho }_{xx}\left(2K\right)]$ of $\approx 3.92$ further indicates the high quality of the films. While at 300 K a weak AHE together with field-linear Hall resistivity (${\rho }_{xy}$) is observed in magnetic fields ($H$) applied perpendicular to the kagome planes, the temperature ($T$) dependence of ${\rho }_{xy}$ shows prominent signatures of three magnetic phases in the temperature regime of 2–300 K. The ${\rho }_{xy}$ also derives a nontrivial topological contribution (${\rho }_{\mathrm{THE}}\sim 1\mathrm{n}\mathrm{\Omega }\mathrm{m}$) in the spin-glass phase which appears at $T\le 100$ K. The origin of the ${\rho }_{\mathrm{THE}}$ is attributed to spin textures which may appear in a frustrated chiral spin order. Our measurements of anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) over a wide $H-T$ phase space reveal the hitherto unseen effects in the three magnetic phases of ${\mathrm{Mn}}_3\mathrm{Sn}$. While the AMR and PHE are negative in the inverse triangular spin phase ($250\mathrm{K}\le T\le T_{\mathrm{N}}$), the helical phase ($100\le T\le 250\mathrm{K}$) is devoid of anisotropic in-plane resistivity, and the spin-glass phase shows a sign reversal of AMR with the increasing magnetic field. The origin of this sign change in AMR/PHE is attributed to the emergence of topologically protected spin textures like skyrmions where the fictitious effective magnetic field is estimated to be $\approx 4.4$ Tesla.

• Received 13 May 2023
• Revised 15 September 2023
• Accepted 13 October 2023

DOI:https://doi.org/10.1103/PhysRevB.108.144435