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Title: Microscopic origin of the spin Seebeck effect
Plain: A temperature difference across a magnetic insulator like yttrium iron garnet drives a spin current into an attached platinum strip, where it appears as a voltage. Which spin waves carry this current, and how lattice vibrations help, is not settled.
Precise: In YIG/Pt the longitudinal spin Seebeck voltage depends on YIG thickness (saturating over lengths of order 1e-4 cm), magnetic field (suppressed at high field), and temperature, with anomalies where magnons and phonons hybridize (magnon polarons, 2016). Determine the roles of bulk thermal-magnon accumulation, the interfacial magnon-electron temperature difference, and magnon-phonon coupling, and predict the voltage versus thickness, T and field. An answer is one quantitative model reproducing all three dependences.
Settled by: A parameter-free model using measured magnon and phonon spectra that reproduces the thickness, field and temperature dependence of the voltage in YIG/Pt.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: Bulk magnon accumulation models describe the thickness dependence and magnon-polaron anomalies show phonons matter; a unified quantitative account is lacking.
Posed since: 2008