Nonlocal magnon-based transport in yttrium-iron-garnet–platinum heterostructures at high temperatures

The spin Hall effect in a heavy metal thin film allows to probe the magnetic properties of an adjacent insulator via magnetotransport measurements. Here, we investigate magnetoresistive response yttrium iron garnet/platinum heterostructures from room temperature beyond Curie $T_\mathrm{C, YIG} \approx 560\,\mathrm{K}$ ferrimagnetic insulator. We find that amplitude (local) magnetoresistance decreases monotonically $300\,\mathrm{K}$ towards $T_\mathrm{C}$, mimicking evolution saturation magnetization garnet. Interestingly, vanishes around $500\,\mathrm{K}$, well below which attribute formation parasitic interface layer by interdiffusion. Around non-local magnon-mediated exhibits power law scaling $T^{\alpha}$ with $\alpha = 3/2$, as already reported. exponent gradually \sim 1/2$ at $420\,\mathrm{K}$, before rapidly similar magnetoresistance. reduced $\alpha$ high temperatures increasing thermal magnon population leads enhanced scattering non-equilibrium and diffusion length. Finally, field independent offset voltage signal for $T > 470\,\mathrm{K}$ associate electronic leakage currents through normally insulating garnet film. Indeed, this is thermally activated energy close band gap.