2026-10-28 九州大学
九州大学の研究グループは、極薄のイリジウムマンガン（IrMn）合金層を磁性体と非磁性体の界面に挿入することで、電子のスピンの流れである「スピン流」の輸送効率が向上することを明らかにした。スピン流は、電子の電荷を直接移動させずに情報を伝えるスピントロニクス技術の基盤であり、低消費電力の次世代情報デバイスへの応用が期待されている。しかし、スピン流は微弱で、効率よく伝達・利用することが課題だった。研究チームは、熱勾配によって磁性体内に生じるスピンゼーベック効果と、電流からスピン流への変換に関わるスピンホール磁気抵抗効果を測定・解析した。さらにナノ構造解析を行い、IrMn層が連続膜ではなく島状に形成されることが、スピン流の伝播効率向上に重要であると突き止めた。この成果は、材料界面の微細構造を制御してスピン流を増強する設計指針を示し、省電力メモリなど次世代電子デバイスの実現に貢献すると期待される。
不連続な島状をなす、ごく薄いIrMnがスピンの輸送効率を向上します。
＜関連情報＞
- https://www.kyushu-u.ac.jp/ja/researches/view/1610
- https://www.sciencedirect.com/science/article/pii/S2542529326002385
Y3Fe5O12とPtの間に挟まれた超薄型IrMn層がスピンゼーベック効果とスピンホール磁気抵抗の増強に果たす役割 Role of ultrathin IrMn layer between Y3Fe5O12 and Pt in enhancement of spin Seebeck effect and spin Hall magnetoresistance
Amirah Zahrin,Shuto Sahara,Yuichiro Kurokawa,Hiroki Hanamoto,Hiromi Yuasa
Materials Today Physics Available online :30 September 2026
DOI:https://doi.org/10.1016/j.mtphys.2026.102247
Highlights
- Significant increase in spin Seebeck voltage by inserting thin IrMn at YIG/Pt interface.
- Spin Hall magnetoresistance does not change even after inserting thin IrMn.
- Onsager relation of spin absorption and pumping explained increase in spin mixing conductance.
- IrMn has a large impact on spin mixing conductance.
Abstract
Manipulation of spin is important for the utilization of spins in electronic devices, and many studies have shown that it strongly depends on the material selection at the interface between magnetic and non-magnetic materials. We investigated the spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) in the laminated YIG/ultra-thin IrMn/Pt structure simultaneously, thereby observing the spin pumping from YIG to Pt through IrMn and the spin absorption from Pt to YIG via IrMn, respectively. By varying the IrMn thickness from 0 to 1 nm, it was found that both the SSE and SMR showed related IrMn thickness dependence, indicating that the effects of IrMn on spin pumping and absorption are analogous. Because the (inverse) spin Hall effect in IrMn is much smaller than that in Pt, the spin Seebeck coefficient and SMR are determined not by the spin Hall angle inside the IrMn, but by the spin mixed conductivity at the two interfaces resulting from the IrMn insertion. The dependence of the spin mixing conductance on the IrMn thickness was derived from the spin Seebeck coefficient and SMR, and the results were in good agreement, demonstrating a reciprocal relationship between the enhancements in spin pumping and absorption owing to IrMn insertion.
