Solution-Processed Ferrimagnetic Insulator Thin Film for the Microelectronic Spin Seebeck Energy Conversion

Abstract

The longitudinal spin Seebeck effects with a ferro- or ferrimagnetic insulator provide a new architecture of a thermoelectric device that could significantly improve the energy conversion efficiency. Until now, epitaxial yttrium iron garnet (YIG) films grown on gadolinium gallium garnet (GGG) substrates by a pulsed laser deposition have been most widely used for spin thermoelectric energy conversion studies. In this work, we developed a simple route to obtain a highly uniform solution-processed YIG film and used it for the on-chip microelectronic spin Seebeck characterization. We improved the film roughness down to ∼0.2 nm because the extraction of thermally induced spin voltage relies on the interfacial quality. The on-chip microelectronic device has a dimension of 200 μm long and 20 μm wide. The solution-processed 20 nm thick YIG film with a 10 nm Pt film was used for the spin Seebeck energy converter. For a temperature difference of Δ T ≈ 0.036 K applied on the thin YIG film, the obtained Δ V ≈ 28 μV, which is equivalent to S ≈ 80.4 nV/K, is close to the typical reported values for thick epitaxial YIG films. The temperature and magnetic field-dependent behaviors of spin Seebeck effects in our YIG films suggest active magnon excitations through the noncoherent precession channel. The effective SSE generation with the solution-processed thin YIG film provides versatile applications of the spin thermoelectric energy conversion.

A scalable molecule-based magnetic thin film for spin-thermoelectric energy conversion

“…The on-chip Au line was also simultaneously used as a temperature sensor 11,23 . An electrical insulation between the top Au heater and Cr-PBA/Cr bilayer was done by the insertion of Al 2 O 3 (130 nm)/Parylene (400 nm) films.…”

“…In particular, Yttrium iron garnet Y 3 Fe 5 O 12 (YIG) has been most widely used for STE applications because its low Gilbert damping constant (α = 2.3 × 10 −4 ) allows long-distance magnon propagation 10 . However, inorganic magnetic insulator films are not appropriate for practical STE applications due to scaling problem, because they are difficult to grow into a large area and in need of high temperature processing for crystallization 3,11 . In contrast, organic or molecular films are generally grown at a lower temperature, and their flexible synthetic routes could offer scalable deposition techniques.…”

Application the Ion Beam Sputtering Deposition Technique for the Development of Spin-Wave Structures on Ferroelectric Substrates

“…The root-mean-square roughness for the former was 0.96-2.84 nm, while for the latter it turned out to be 4-6.5 nm. In thinner films of yttrium iron garnet (20 nm), obtained in [39] by chemical solution deposition on oxidized silicon substrates and annealed at 800 • C, R q reached a subnanoscale value of 0.2 nm. These results are not unexpected, since they were obtained on sufficiently smooth substrates with a regular surface.…”

Magnetoimpedance of Epitaxial Y3Fe5O12 (001) Thin Film in Low-Frequency Regime

“…Yttrium iron garnet (YIG, Y 3 Fe 5 O 12 ) is a well-known ferrimagnetic insulator with a low damping factor of ∼10 –5 and is among the prevalent choices to study spin current-related transport phenomena such as the spin Seebeck effect, spin Hall magnetoresistance, spin–orbit magnetoresistance, spin pumping, spin pumping-inverse spin Hall effect measurements, etc. − The low Gilbert damping factor of YIG allows the transfer of the spin information over long distances without unwanted spurious effects otherwise observed in metallic ferromagnets. ,,− Further, the structural quality of the YIG thin film and its magnetic properties such as effective magnetization, the gyromagnetic ratio, anisotropy fields, and magnon–magnon interaction also play a crucial role in realizing spin transport across YIG and its heterointerfaces with heavy metals . Therefore, a comprehensive investigation of the magnetization dynamics of YIG, below and above the anisotropy field, is essential to gain detailed insight and accurately determine its magnetic properties. , The conventional technique employed to study the magnetization dynamics and to estimate the aforementioned magnetic parameters is the ferromagnetic resonance (FMR) .…”