Year: 2020
Type: article
Abstract: The magnon diffusion length (MDL) is understood to play a major role in the thickness dependence of spin Seebeck effect (SSE) voltages in ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}/\mathrm{Pt}$ thin films. Here we extract the MDL in an ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ single crystal using inelastic neutron scattering (INS) and in ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}/\mathrm{Pt}$ thin films using accurate heat flux SSE and static magnetization measurements. The INS MDLs were $34\ifmmode\pm\else\textpm\fi{}8\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $300\phantom{\rule{4pt}{0ex}}\mathrm{K}$ and $27\ifmmode\pm\else\textpm\fi{}6\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $50\phantom{\rule{4pt}{0ex}}\mathrm{K}$. The SSE MDLs decreased with temperature ($19\ifmmode\pm\else\textpm\fi{}2\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $300\phantom{\rule{4pt}{0ex}}\mathrm{K}$ and $13\ifmmode\pm\else\textpm\fi{}4\phantom{\rule{4pt}{0ex}}\mathrm{nm}$ at $50\phantom{\rule{4pt}{0ex}}\mathrm{K}$), but were markedly smaller. Whilst the bulk MDL is expected to be an upper limit of the MDL in thin films, we show that the film magnetization must be considered to obtain MDLs from SSE measurements. This study highlights the importance of disentangling the role of various effects in SSE measurements which is crucial in increasing the efficiencies of thermomagnetic energy harvesting devices.
Source: Physical Review Materials
Language: Latvian
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W3042625829