Absence of magnetic order and magnetic fluctuations in RuO${}_2$

Abstract

A novel magnetic class blending ferromagnetism and antiferromagnetism, termed altermagnetism, has gained significant attention for its staggered order in coordinate and momentum spaces, time-reversal symmetry-breaking phenomena, and promising applications in spintronics. Ruthenium dioxide (RuO${}_2$) has been considered a candidate material for altermagnetism, yet the presence of magnetic moments on Ru atoms remains a subject of debate. In this study, we systematically investigated the magnetic properties of RuO${}_2$ powder using nuclear quadrupole resonance (NQR) measurements. The NQR spectra show that there is no internal magnetic field. Furthermore, the temperature independence of spin-lattice relaxation rate, $1/T_{1}T$, proves that there are no magnetic fluctuations. Our results unambiguously demonstrate that Ru atoms in RuO${}_2$ possess neither static magnetic moments nor fluctuating magnetic moments, and thus RuO${}_2$ does not possess the magnetic characteristics essential for altermagnetism.

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