We characterize spin-wave propagation and its modification by an electrical current in permalloy($\mathrm{Py}$)/$\mathrm{Pt}$ bilayers with $\mathrm{Py}$ thickness between 4 and 20 nm. First, we analyze the frequency nonreciprocity of surface spin waves and extract from it the interfacial Dzyaloshinskii-Moriya interaction constant $D_s$ accounting for an additional contribution due to asymmetric surface anisotropies. Second, we measure the spin-wave relaxation rate and deduce from it the $\mathrm{Py}$/$\mathrm{Pt}$ spin-mixing conductance $g_{\mathrm{eff}}^{\uparrow \downarrow }$. Last, applying a dc electrical current, we extract the spin Hall conductivity ${\sigma }_{\mathrm{SH}}$ from the change of spin-wave relaxation rate due to the spin Hall spin-transfer torque. We obtain a consistent picture of the spin-wave propagation data for different film thicknesses using a single set of parameters $D_s=0.25$ pJ/m, $g_{\mathrm{eff}}^{\uparrow \downarrow }=3.2\times {10}^{19}{\mathrm{m}}^{-2}$ and ${\sigma }_{\mathrm{SH}}=4\times {10}^5$ S/m.

• Received 30 August 2019
• Revised 5 November 2019

DOI:https://doi.org/10.1103/PhysRevApplied.13.014016