Local and nonlocal spin Seebeck effect in lateral Pt-$\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$-Pt devices at low temperatures

Abstract

We have studied thermally driven magnon spin transport (spin Seebeck effect, SSE) in heterostructures of antiferromagnetic $\alpha$-$\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$ and Pt at low temperatures. Monitoring the amplitude of the local and nonlocal SSE signals as a function of temperature, we found that both decrease with increasing temperature and disappear above 100 K and 20 K, respectively. Additionally, both SSE signals show a tendency to saturate at low temperatures. The nonlocal SSE signal decays exponentially for intermediate injector-detector separation, consistent with magnon spin current transport in the relaxation regime. We estimate the magnon relaxation length of our $\alpha$-$\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_3$ films to be around 500 nm at 3 K. This short magnon relaxation length along with the strong temperature dependence of the SSE signal indicates that temperature-dependent inelastic magnon scattering processes play an important role in the intermediate range magnon transport. Our observation is relevant to low-dissipation antiferromagnetic magnon memory and logic devices involving thermal magnon generation and transport.

Accepted in APL Materials, For Supplementary Material see published version

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