Recently the topic of altermagnetism has attracted tremendous attention, and ${\mathrm{RuO}}_2$ has been demonstrated to be one of the most promising altermagnetic candidates. However, disputes still remain on the existence of magnetic order in ${\mathrm{RuO}}_2$. Here in this work, we employ x-ray linear dichroism (XLD), a widely utilized technique for characterizing antiferromagnets, in conjunction with photoemission electron microscopy and multiple scattering calculation to provide clear evidence of the absence of magnetic order in epitaxial ${\mathrm{RuO}}_2$ films. The observed XLD signal is nearly invariant with temperature and independent of cooling-field direction, in stark contrast to the substantial magnetic-order-related XLD signal predicted by multiple scattering calculation. This finding strongly suggests a nonmagnetic origin for ${\mathrm{RuO}}_2$. Furthermore, we observed significantly distinct XLD signals at the Ru $M_3$ and O $K$ edges in ${\mathrm{RuO}}_2$ films grown on ${\mathrm{TiO}}_2$ substrate with different surface orientations, which can be attributed to the low-symmetry crystal field. These results unequivocally demonstrate the absence of magnetic order in ${\mathrm{RuO}}_2$ and establish XLD measurement as a robust technique for probing the low-symmetry magnetic materials.

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• Altermagnetism
• Magnetic order
• Magnetism
• Thin films
• Transition metal oxides
• X-ray magnetic linear dichroism
• X-ray photoemission electron microscopy