Improving the spin mixing conductance at the ferromagnet/heavy metal (FM/HM) interface with a low Gilbert damping constant in the FM layer is a key requirement for developing efficient spintronic devices. To evaluate the potential of Co₂FeGa₀. ₅Ge₀. ₅ as the FM layers in such structures, epitaxial Co₂FeGa₀. ₅Ge₀. ₅ single-layer and Co₂FeGa₀. ₅Ge₀. ₅/Pt bilayer films were deposited on MgO substrates using magnetron sputtering, and their Gilbert damping constants were evaluated from ferromagnetic resonance spectra. While the single-layer samples exhibit a low damping constant of 1. 0710^-3, an enhancement in the damping constant was observed in the bilayer samples due to spin pumping across the Co₂FeGa₀. ₅Ge₀. ₅/Pt interface, from which relatively large spin mixing conductance (g₄₅₅^) of (2. 780. 09) 10^190. 16em{0ex}m^-2 was evaluated. Further, to investigate the effect of interface property on g₄₅₅^, ultrathin (0. 2 nm) Cu, Ni, Ru, Ta, or Cr insertion layers were introduced between the Co₂FeGa₀. ₅Ge₀. ₅ and Pt. Inserting a nonmagnetic (NM) Cu layer results in a pronounced decrease of g₄₅₅^, whereas the FM Ni layer leaves g₄₅₅^ nearly unchanged. In the case of Ru and Ta insertion layers, a modest reduction in g₄₅₅^ is observed despite their NM nature. The antiferromagnetic Cr insertion layer also causes a small decrease in g₄₅₅^. The observed change in g₄₅₅^ depends on the insertion material, indicating that their physical properties, such as magnetic, nonmagnetic, antiferromagnetic, light or heavy metal, reflect on g₄₅₅^.
Bhat et al. (Wed,) studied this question.