Absence of magnetic order and magnetic fluctuations in RuO$_{2}$

TL;DR

This study uses nuclear quadrupole resonance to show that RuO₂ lacks magnetic moments and fluctuations, indicating it does not exhibit altermagnetism or related magnetic properties.

Contribution

The paper provides direct experimental evidence that RuO₂ does not have magnetic moments or fluctuations, clarifying its magnetic nature and ruling out its candidacy for altermagnetism.

Findings

No internal magnetic field detected in RuO₂

Spin-lattice relaxation rate is temperature independent

Ru atoms have no static or fluctuating magnetic moments

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, $1/T_1T$, 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.