2025-06-18 物質・材料研究機構
図: (a) TMR振動現象が生じる仕組みの模式図。磁性層と絶縁層の界面における波動関数の重ね合わせが鍵となる。
(b) 理論計算と実験データの比較。計算結果は様々な条件で実験結果とよく一致し、TMR振動現象を再現している。
＜関連情報＞
- https://www.nims.go.jp/press/2025/06/202506180.html
- https://www.nims.go.jp/press/2025/06/f5rpo6000000cxoq-att/202506180.pdf
- https://journals.aps.org/prb/abstract/10.1103/PhysRevB.111.L220406
トンネル磁気抵抗振動の理論 Theory for tunnel magnetoresistance oscillation
Keisuke Masuda, Thomas Scheike, Hiroaki Sukegawa, Yusuke Kozuka, Seiji Mitani, and Yoshio Miura
Physical Review B Published: 9 June, 2025
DOI: https://doi.org/10.1103/PhysRevB.111.L220406
Abstract
The universal oscillation of the tunnel magnetoresistance (TMR) ratio as a function of the insulating barrier thickness in crystalline magnetic tunnel junctions (MTJs) is a long-standing unsolved problem in condensed matter physics. To explain this, we here introduce a superposition of wave functions with opposite spins and different Fermi momenta, based on the fact that spin-flip scattering near the interface provides a hybridization between majority- and minority-spin states. In a typical Fe/MgO/Fe MTJ, we solve the tunneling problem and show that the TMR ratio oscillates with a period of ∼3Å by varying the MgO thickness, consistent with previous and present experimental observations.
