Universal scaling behavior of transport properties in non-magnetic RuO2

As a prototypical altermagnet, RuO2 has been subject to many controversial reports regarding its magnetic ground state and the existence of the crystal Hall effect. We obtained a high-quality RuO2 single crystal with a residual resistivity ratio (RRR = 152), and carefully measured its magnetization, longitudinal resistivity (ρxx) and Hall resistivity (ρyx) in magnetic field up to 35 T. We also calculated its electronic bands and Fermi surface, and conducted numerical simulations for its transport properties. It was found that no magnetic transition occurs below 400 K, and that all the transport properties are consistent with the numerical simulation results, indicating that the magneto-transport properties originate from the intrinsic electronic structure and are dominated by the Lorentz force. Particularly, no crystal Hall effects were observed in our RuO2 samples and both magnetoresistance and Hall resistivity follow a scaling behavior. Additionally, by comparing theoretical calculations with experimental data, we found that the magneto-transport properties calculated using the altermagnetic structure are not consistent with the experimental observations, whereas those calculated based on the non-magnetic structure show excellent agreement. These results demonstrate that RuO2 is a typical semimetal, rather than an altermagnet. The altermagnet candidate RuO2 has sparked recent debate in the scientific community regarding its magnetic ground state and the existence of a crystal Hall effect. Here, the authors synthesize high-quality RuO2 crystals and provide comprehensive measurements to reveal that its magneto-transport properties obey scaling law and align with a non-magnetic semimetal model, challenging the notion of RuO2 as an altermagnet and refining our understanding of its electronic structure.