Separation of Rare-Earth and Transition-Metal Contributions to the Interfacial Dzyaloshinskii-Moriya Interaction in Ferrimagnetic Co - Gd Alloys

Ferrimagnetic materials composed of rare earth (RE) and transition metals (TM) are of great interest for spintronic devices due to their tunable net moments and magnetic transport behaviors. Here we experimentally study the Dzyaloshinskii-Moriya interaction (DMI) in $\mathrm{Co}\text{\ensuremath{-}}\mathrm{Gd}$ ferrimagnets and find that the DMI strength increases substantially as the temperature approaches its moment compensation point. By subtracting the contribution of Heisenberg exchange coupled $\mathrm{Co}$-$\mathrm{Co}$ moments mediated by $\mathrm{Pt}$ from the total DMI strength, we observe a relationship ${D}_{\text{Co - Gd}}\ensuremath{\sim}{M}_{s}^{0.2\ifmmode\pm\else\textpm\fi{}0.06}$. The lower order indicates the weaker Heisenberg exchange compared with $\mathrm{Co}$-$\mathrm{Co}$ moments in $\mathrm{Co}\text{\ensuremath{-}}\mathrm{Gd}$ alloys. Our results reveal the intrinsic physics of DMI in RE-TM alloys by separating the different contributions of TM-TM and RE-TM sublattice moments from the total DMI and show the promising prospect for the fabrication of skyrmions in RE-TM ferrimagnets near the compensation point.