  Electrical manipulation of emergent phenomena due to nontrivial band topology
is a key to realize next-generation technology using topological protection. A
Weyl semimetal is a three-dimensional gapless system that hosts Weyl fermions
as low-energy quasiparticles. It exhibits various exotic phenomena such as
large anomalous Hall effect (AHE) and chiral anomaly, which have robust
properties due to the topologically protected Weyl nodes. To manipulate such
phenomena, the magnetic version of Weyl semimetals would be useful as a
magnetic texture may provide a handle for controlling the locations of Weyl
nodes in the Brillouin zone. Moreover, given the prospects of antiferromagnetic
(AF) spintronics for realizing high-density devices with ultrafast operation,
it would be ideal if one could electrically manipulate an AF Weyl metal.
However, no report has appeared on the electrical manipulation of a Weyl metal.
Here we demonstrate the electrical switching of a topological AF state and its
detection by AHE at room temperature. In particular, we employ a
polycrystalline thin film of the AF Weyl metal Mn$_3$Sn, which exhibits
zero-field AHE. Using the bilayer device of Mn$_3$Sn and nonmagnetic metals
(NMs), we find that an electrical current density of $\sim 10^{10}$-$10^{11}$
A/m$^2$ in NMs induces the magnetic switching with a large change in Hall
voltage, and besides, the current polarity along a bias field and the sign of
the spin Hall angle $\theta_{\rm SH}$ of NMs [Pt ($\theta_{\rm SH} > 0$),
Cu($\theta_{\rm SH} \sim 0$), W ($\theta_{\rm SH} < 0$)] determines the sign of
the Hall voltage. Notably, the electrical switching in the antiferromagnet is
made using the same protocol as the one used for ferromagnetic metals. Our
observation may well lead to another leap in science and technology for
topological magnetism and AF spintronics.

Materials Science;Mesoscale and Nanoscale Physics;Strongly Correlated Electrons