Spin Injection through Organic Molecules with Varied Spin Sources

Sheng-Yueh Weng^1*, M Sanjoy Singh¹, Cheng-Fong Hong¹, Wen-Teng Lin¹, Po-Hsun Wu¹, Ssu-Yen Huang¹, Jauyn Grace Lin², Yu-Hsun Chu¹, Wen-Chung Chiang³, Minn-Tsong Lin^1,4,5

¹Department of Physics, National Taiwan University, Taipei, Taiwan
²Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
³Department of Optoelectric Physics, Chinese Culture University, Taipei, Taiwan
⁴Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
⁵Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Sheng-Yueh Weng, email:l27024732@gmail.com

Spin pumping and the longitudinal spin Seebeck effect (LSSE) are the emerging techniques of the spin injection, and they have been applied in our devices with π-conjugated organic semiconducting spacer, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). In spin pumping, to verify the magnetization and the gyromagnetic ratio, angle-dependent measurements were performed, and the PTCDA-thickness-dependent voltage determined the spin diffusion length in PTCDA. Furthermore, a normalization factor has been introduced to the spin pumping analysis to eliminate the voltage contributed by the deviation of the spin sources for a more accurate spin diffusion length. While spin pumping with permalloy as a spin source guarantees the spin transport through PTCDA, the LSSE from yttrium iron garnet shows no convincing sign of injection. These results are attributed to the interfaces between spin sources and organic semiconductors; the type of injection and the choice of material combination are both crucial.

Keywords: spin injection, spin pumping, spin Seebeck effect, organic semiconductor