Effective spin injection into the organic semiconductor PTCDA evaluated by a normalization method
Journal
Applied Physics Letters
Journal Volume
121
Journal Issue
23
Date Issued
2022-12-05
Author(s)
Weng, Sheng Yueh
Singh, M. Sanjoy
Hong, Cheng Feng
Lin, Wen Teng
Wu, Po Hsun
Chu, Yu Hsun
Chiang, Wen Chung
Abstract
Studies of spin current injection, transport, and interface control have drawn attention recently for efficient organic spintronic devices. In this study, we apply both spin pumping (SP) and the longitudinal spin Seebeck effect (LSSE) to inject spin currents into a π-conjugated organic semiconductor, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), and characterize injection and transport by measuring inverse spin Hall voltage V ISHE in spin detectors. A normalization factor introduced to SP analysis eliminates a contribution provoked by deviation of spin sources and leads to a more accurate determination of the spin diffusion length in PTCDA. While SP with Permalloy as a spin source is effective in generating detectable V ISHE, the LSSE from yttrium iron garnet shows no convincing sign of spin injection. In addition, spin-flip scattering induced by hybrid states undermining electrical spin injection is negligible in SP. These results are attributed to interfaces between spin sources and PTCDA, indicative of the importance of injection methods and material choices.
Type
journal article