Anomalous Antiferromagnetism in Metallic RuO${}_2$ Determined by Resonant X-ray Scattering

We studied the magnetic ordering of thin films and bulk crystals of rutile RuO${}_2$ using resonant X-ray scattering across the Ru L${}_2$ absorption edge. Combining polarization analysis and azimuthal-angle dependence of the magnetic Bragg signal, we have established the presence of G-type antiferromagnetism in RuO${}_2$ with T${}_N$ $>$ 300 K. In addition to revealing a spin-ordered ground state in the simplest ruthenium oxide compound, the persistence of magnetic order even in nanometer-thick films lays the ground for potential applications of RuO${}_2$ in antiferromagnetic spintronics.