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Chen, Y.*; 佐藤 正寛*; Tang, Y.*; 塩見 雄毅*; 大柳 洸一*; 益田 隆嗣*; 南部 雄亮*; 藤田 全基*; 齊藤 英治
Nature Communications (Internet), 12, p.5199_1 - 5199_7, 2021/08
被引用回数：9 パーセンタイル：63.91(Multidisciplinary Sciences)A triplon refers to a fictitious particle that carries angular momentum 
corresponding to the elementary excitation in a broad class of quantum dimerized spin systems. Such systems without magnetic order have long been studied as a testing ground for quantum properties of spins. Although triplons have been found to play a central role in thermal and magnetic properties in dimerized magnets with singlet correlation, a spin angular momentum flow carried by triplons, a triplon current, has not been detected yet. Here we report spin Seebeck effects induced by a triplon current: triplon spin Seebeck effect, using a spin-Peierls system CuGeO
. The result shows that the heating-driven triplon transport induces spin current whose sign is positive, opposite to the spin-wave cases in magnets. The triplon spin Seebeck effect persists far below the spin-Peierls transition temperature, being consistent with a theoretical calculation for triplon spin Seebeck effects.
大門 俊介*; 内田 健一*; 氏家 奈緒美*; 服部 靖之*; 坪井 嶺*; 齊藤 英治
Applied Physics Express, 13(10), p.103001_1 - 103001_4, 2020/10
被引用回数：7 パーセンタイル：43.4(Physics, Applied)Magnon propagation length in a ferrimagnetic insulator yttrium iron garnet (YIG) has been investigated by measuring and analyzing the YIG-thickness 
dependence of the spin Peltier effect (SPE) in a Pt/YIG junction system. By means of the lock-in thermography technique, we measured the spatial distribution of the SPE-induced temperature modulation in the Pt/YIG system with the gradation, allowing us to obtain the accurate dependence of SPE with high resolution. Based on the dependence of SPE, we verified the applicability of several phenomenological models to estimate the magnon diffusion length in YIG.
八尋 黎明*; 吉川 貴史*; Ramos, R.*; 大柳 洸一*; 日置 友智*; 大門 俊介*; 齊藤 英治
Physical Review B, 101(2), p.024407_1 - 024407_7, 2020/01
被引用回数：20 パーセンタイル：77.19(Materials Science, Multidisciplinary)We report the observation of anomalous peak structures induced by hybridized magnon-phonon excitation (magnon polarons) in the magnetic field dependence of the spin Peltier effect (SPE) in a Lu
Bi
Fe
GaO
(BiGa:LuIG) with Pt contact. The SPE peaks coincide with magnetic fields tuned to the threshold of magnonpolaron formation, consistent with the previous observation in the spin Seebeck effect. The enhancement of SPE is attributed to the lifetime increase in spin current caused by magnon-phonon hybridization in BiGa:LuIG.
大沼 悠一; 松尾 衛*; 前川 禎通; 齊藤 英治
まぐね, 12(5), p.217 - 224, 2017/10
熱とスピンの相互変換現象であるスピンゼーベック効果及びスピンペルチェ効果について微視的理論に基づき議論を行う。まずはじめに、熱流からスピン流を生成するスピンゼーベック効果について議論する。スピンゼーベック効果の最近の進展を紹介し、フェリ磁性体でのスピンゼーベック効果の符号反転について説明する。次に、スピン流による熱流生成法であるスピンペルチェ効果について議論する。最後に、スピンゼーベック効果とスピンペルチェ効果がオンサーガの相反関係によってまとめられることを示し、スピンと熱の輸送に関するケルビンの関係式を導出する。
