A research team led by Dr. Keisuke Masuda and Dr. Yoshio Miura has developed a new theory that explains why tunnel magnetoresistance (TMR) oscillates with changes in the thickness of the insulating barrier within a magnetic tunnel junction (MTJ).
2025.08.06
A research team led by Dr. Keisuke Masuda (Senior Researcher, Spin Theory Group) and Dr. Yoshio Miura (Visiting Researcher) has developed a new theory that explains why tunnel magnetoresistance (TMR) —used in magnetic memory and other technologies— oscillates with changes in the thickness of the insulating barrier within a magnetic tunnel junction (MTJ). This oscillation was clearly observed when NIMS recently recorded the world’s highest TMR ratio. Understanding the mechanisms behind this phenomenon is expected to significantly aid in further increasing TMR ratios.
K. Masuda, T. Scheike, H. Sukegawa, Y. Kozuka, S. Mitani, and Y. Miura, "Theory for tunnel magnetoresistance oscillation", Physical Review B 111, L220406 (2025)
Figure. (a) Schematic illustration of the mechanism for the TMR oscillation. A superposition of wave functions at the interface of the MTJ is considered—a key to this mechanism. (b) Comparison between theoretical and experimental values of the TMR ratio. The agreement between theoretical and experimental values demonstrates the validity of the present theory.