Criteria for accurate determination of the magnon relaxation length from the nonlocal spin Seebeck effect

Abstract

The nonlocal transport of thermally generated magnons not only unveils the underlying mechanism of the spin Seebeck effect, but also allows for the extraction of the magnon relaxation length (${\lambda }_m$) in a magnetic material, the average distance over which thermal magnons can propagate. In this study, we experimentally explore in yttrium iron garnet (YIG)/platinum systems much further ranges compared with previous investigations. We observe that the nonlocal SSE signals at long distances ($d$) clearly deviate from a typical exponential decay. Instead, they can be dominated by the nonlocal generation of magnon accumulation as a result of the temperature gradient present away from the heater, and decay geometrically as $1/d^2$. We emphasize the importance of looking only into the exponential regime (i.e., the intermediate distance regime) to extract ${\lambda }_m$. With this principle, we study ${\lambda }_m$ as a function of temperature in two YIG films which are 2.7 and 50 $\mu$m in thickness, respectively. We find ${\lambda }_m$ to be around 15 $\mu$m at room temperature and it increases to 40 $\mu$m at $T=$ 3.5 K. Finite element modeling results agree with experimental studies qualitatively, showing also a geometrical decay beyond the exponential regime. Based on both experimental and modeling results we put forward a general guideline for extracting ${\lambda }_m$ from the nonlocal spin Seebeck effect.

9 pages, 7 figures

References in corpus (11)

• Spin Seebeck insulator
• Magnon Polarons in the Spin Seebeck Effect
• Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect at High Temperatures
• Simultaneous detection of the spin-Hall magnetoresistance and the spin-Seebeck effect in Platinum and Tantalum on Yttrium Iron Garnet
• Temperature dependence of the magnon spin diffusion length and magnon spin conductivity in the magnetic insulator yttrium iron garnet
• Influence of yttrium iron garnet thickness and heater opacity on the nonlocal transport of electrically and thermally excited magnons
• Nonlocal magnon-polaron transport in yttrium iron garnet
• Thermally Driven Long Range Magnon Spin Currents in Yttrium Iron Garnet due to Intrinsic Spin Seebeck Effect
• Lateral transport properties of thermally excited magnons in yttrium iron garnet films
• Spintronics and Magnon Bose-Einstein Condensation
• Temperature dependence of the non-local spin Seebeck effect in YIG/Pt nanostructures

Cited by in corpus (3)

• Magnon transport in quasi-two-dimensional van der Waals antiferromagnets
• Thermally Driven Long Range Magnon Spin Currents in Yttrium Iron Garnet due to Intrinsic Spin Seebeck Effect
• Magnetic field dependence of the nonlocal spin Seebeck effect in Pt/YIG/Pt systems at low temperatures