Numerical study on the spin Seebeck effect

スピンゼーベック効果に対する数値解析

大江 純一郎; 安立 裕人; 高橋 三郎; 前川 禎通

Oe, Junichiro; Adachi, Hiroto; Takahashi, Saburo; Maekawa, Sadamichi

熱勾配によって誘起される強磁性絶縁体中のスピン波について理論解析を行った。特に、非磁性端子によって観測されるスピン波スピン流の電気的シグナルを計算できる数値シミュレーション法を開発した。揺動散逸定理により温度勾配中の磁化の運動を再現し、計算によって得られたシグナルは実験と良い一致を示した。

Thermally driven spin-wave spin currents in ferromagnetic (FM) materials and a resulting measurable electric signal in a normal metal (NM) probe placed on FM are theoretically investigated. We develop the numerical technique for calculating a spin Seebeck signal detected by the NM probe that converts the spin current to the charge current. By taking into account the fluctuation-dissipation theorem for thermally fluctuating spins at the interface of a FM/NM junction, the spin current is induced in the NM probe via an exchange interaction when the FM feels the temperature gradient. Numerical simulation clarifies the role of the sample boundary on the spatial distribution of the spin current both in FM and NM. The spin-wave spin current that flows parallel to the heat current is also investigated.