Enhanced antiferromagnetic resonance linewidth in NiO/Pt and NiO/Pd

In this paper, we investigate the enhancement of the antiferromagnetic damping in the sintered NiO-HM (where HM is heavy metal) granular systems having NiO/HM interfaces, where $\mathrm{HM}=\mathrm{Pt}$ or Pd. Under the assumption of the spin pumping model, we derive the effective interfacial damping conductance ${g}_{\mathrm{eff}}$, the parameter which characterizes the upper-bound estimate of the spin pumping effect, to be $12\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.16em}{0ex}}\mathrm{n}{\mathrm{m}}^{\ensuremath{-}2}$ and $5\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.16em}{0ex}}\mathrm{n}{\mathrm{m}}^{\ensuremath{-}2}$ for the NiO/Pt and the NiO/Pd interfaces, respectively, at room temperature. ${g}_{\mathrm{eff}}$ experimentally derived in this study are an important milestone in antiferromagnetic spintronics, giving a guideline for various spin current transfer and spin interaction phenomena with antiferromagnets where the spin mixing conductance is involved.