Probing for an altermagnetic ground state in Ru_1-xCr_xO₂

In recent years, RuO₂ has received significant attention as an altermagnetic candidate material, however the most direct probes of the magnetic ground state using neutron scattering and muon spin rotation strongly point to it being a normal metal. Although stoichiometric RuO₂ is non-magnetic, theory suggests that hole doping via Ru vacancies or by alloying with Cr atoms could induce altermagnetism. We investigated this proposal by growing Ru_1-xCr_xO₂ thin films using reactive magnetron co-sputtering, focusing on compositions near x ≈ 0.2 which is expected to provide sufficient hole doping to achieve an altermagnetic ground state. In this talk, I will report on the structural and magnetic properties of Ru_0.8Cr_0.2O₂ using a range of X-ray and neutron scattering techniques in order to shed light on its putative altermagnetic state.