Large Spin Hall Conductivity in Epitaxial Thin Films of Kagome Antiferromagnet Mn3Sn at Room Temperature

Mn3Sn is a non‐collinear antiferromagnetic quantum material that exhibits a magnetic Weyl semimetallic state and has great potential for efficient memory devices. High‐quality epitaxial c‐plane Mn3Sn thin films have been grown on a sapphire substrate using a Ru seed layer. Using spin pumping induced inverse spin Hall effect measurements on c‐plane epitaxial Mn3Sn/Ni80Fe20, spin‐diffusion length (λMn3Sn$\lambda _{\rm Mn_3Sn}$), and spin Hall conductivity (σSH) of Mn3Sn thin films are measured: λMn3Sn=0.42±0.04$\lambda _{\rm Mn_3Sn}=0.42\pm 0.04$ nm and σSH=−702ℏ/eΩ−1${\sigma}_{\mathrm{SH}}=-702\ \hslash /e\ {\Omega}^{-1}$cm−1. While λMn3Sn$\lambda _{\rm Mn_3Sn}$ is consistent with earlier studies, σSH is an order of magnitude higher and of the opposite sign. The behavior is explained on the basis of excess Mn, which shifts the Fermi level in these films, leading to the observed behavior. These findings demonstrate a technique for engineering σSH of Mn3Sn films by employing Mn composition for functional spintronic devices. Non‐collinear antiferromagnetic quantum materials have gained attention as alternative spin Hall materials for spin‐to‐charge conversion. This work presents direct measurement of spin Hall conductivity (σSH) in high‐quality c‐plane oriented Mn3Sn thin films. The σSH of epitaxial Mn3Sn thin films is found to be −702 ℏeΩ−1$\frac{\hbar }{e} \Omega ^{-1}$ cm−1. The demonstration of large σSH would accelerate the development of antiferromagnetic‐based spintronic devices.