Ab initio study of quantum oscillations in altermagnetic and nonmagnetic phases of RuO2

The altermagnet (AM) is a magnetic state with collinear antiferromagnetic ground state but it presents some transport properties that were only believed to exist in ferromagnets or noncollinear antiferromagnets. To have a comprehensive understanding of the transport properties of AMs, especially from the experimental point of view, a promising altermagnetic metal is crucial. In all the proposed altermagnetic metals, ${\mathrm{RuO}}_{2}$ has a special position, since it is the AM with the largest spin splitting and several important altermagnetism featured experiments were performed based on it. However, a very recent report based on sensitive muon-spin measurements suggests a supersmall local magnetization from Ru, i.e., a nonmagnetic ground state in ${\mathrm{RuO}}_{2}$. Therefore, a determination of the existence of the altermagnetic ground state is the basic starting point for all the previously altermagnetic transport properties in ${\mathrm{RuO}}_{2}$. In this work, we propose to identify its magnetic ground state from the Fermi surface (FS) via the electronic transport property of quantum oscillation (QO). We systematically analyzed the FSs of ${\mathrm{RuO}}_{2}$ in both nonmagnetic and altermagnetic states via first principles calculations. Our work should be helpful for future experiments on QO measurements to confirm its ground state by the interplay between transport measurements and computations.