Phase Transition and Oxidation Dependence of Charge–Spin Conversion in Rare‐Earth Gadolinium

The rare‐earth metal gadolinium (Gd) is characterized by strong spin‐orbit coupling and a paramagnetic‐to‐ferromagnetic phase transition that enables modulation of a charge–spin conversion via temperature. Charge–spin conversion is experimentally observed and the conversion efficiency is ≈0.26, which is slightly larger than that for Pt and Ta and smaller than that for W. The temperature dependence of charge–spin conversion initially decreases, followed by increasing, because of the paramagnetic‐to‐ferromagnetic phase transition. The charge–spin conversion efficiencies arising from the bulk‐spin Hall effect and the interfacial Rashba–Edelstein effect, respectively, via MgO/Gd/Py and MgO/Py/GdO x systems, are distinguished. The latter has a more significant enhancement because of ambient oxidation that generates the Gd/GdO x interface. The possibility of modulating the conversion efficiency via temperature and oxidation enables applications in spintronic and oxide electronic devices.