{"title":"Spin-Thermoelectric Generation Associated with Magnetization Dynamics in the Insulator-Based Generators Fabricated from Liquid Phase Epitaxial Yttrium Iron Garnet, Bi-Substituted YIG and Bi- and Al-Substituted YIG Films","authors":"Masaaki Imamura, Hironori Asada, Ryota Matsuda, Daisuke Tashima, Jiro Kitagawa","doi":"10.1002/tee.24137","DOIUrl":"10.1002/tee.24137","url":null,"abstract":"<p>An insulator-based spin-thermoelectric (STE) generator is composed of a thin paramagnetic metal (PM: Pt) layer for generating the STE voltage <i>V</i><sub>STE</sub> via the inverse spin Hall effect and a ferrimagnetic insulator (FMI) film or slab used for producing spin-wave spin currents due to a temperature gradient <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∇</mo>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <annotation>$$ nabla T $$</annotation>\u0000 </semantics></math>. Yttrium iron garnet (YIG) is a key material used for the FMI of STE generators. We examined in detail the ferromagnetic resonance (FMR) properties of YIG (Y<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub>), Bi-substituted YIG (Y<sub>3-<i>x</i></sub>Bi<sub><i>x</i></sub>Fe<sub>5</sub>O<sub>12</sub>) and Bi- and Al-substituted YIG (Y<sub>3-<i>x</i></sub>Bi<sub><i>x</i></sub>Fe<sub>5-y</sub>Al<sub><i>y</i></sub>O<sub>12</sub>) films grown by liquid phase epitaxy (LPE). Bi-substituted YIG films exhibited the large FMR damping and high STE voltage when the films were incorporated in the STE generator. The LPE-grown Y<sub>2.35</sub>Bi<sub>0.65</sub>Fe<sub>5</sub>O<sub>12</sub> film exhibited the FMR linewidth Δ<i>H</i> of 30 mT and the <i>V</i><sub>STE</sub> of 70 μV for the ∇<i>T</i> of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>90</mn>\u0000 <mo>×</mo>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>3</mn>\u0000 </mrow>\u0000 </msup>\u0000 <mo>°</mo>\u0000 <mi>C</mi>\u0000 <mo>/</mo>\u0000 <mi>μm</mi>\u0000 </mrow>\u0000 <annotation>$$ 90times {10}^{-3{}^{circ}}C/upmu mathrm{m} $$</annotation>\u0000 </semantics></math>. This paper comprehensively presents the origin of the STE generation in the insulator-based generators on the basis of the results of FMR and STE measurements. To clarify the origin of STE generation in the generators fabricated from single crystal YIG (YIG, Bi-substituted YIG and Bi- and Al-substituted YIG) films grown by LPE, three principal factors are explained: (a) thermal energy transfer from the phonon system to the spin system, which strengthens the heat excitation of spin precession, through the spin–orbit coupling enhanced by the growth-induced magnetic anisotropy of LPE-grown YIG films, (b) in the YIG films incorporated in the STE generators, the generation of spin-wave spin currents owing its origin to the ferromagnetic spin exchange interaction acting between neighboring spins due to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∇</mo>\u0000 <mi>T</mi>\u0000 </mrow>\u0000 <annotation>$$ nabla T $$</annotation>\u0000 </semantics></math>, and (c) how the sp","PeriodicalId":13435,"journal":{"name":"IEEJ Transactions on Electrical and Electronic Engineering","volume":"19 11","pages":"1770-1780"},"PeriodicalIF":1.0,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141367907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}