| 研究実績の概要 |
Langmuir-Blodgett (LB) nanosheets of ferroelectric poly(vinylidene fluoride) were applied to develop memory devices including resistive non-volatile memories and spin-valves, etc. First, ferroelectric PVDF/semiconductive polythiophene (P3CPenT) hybrid monolayers were successfully developed at varying blend ratios from the bottom-up method. The thickness of the multilayered hybrid nanosheet was controlled at 2 nm precision and show improved surface roughness making it more applicable for electronics than spin-cast films. More importantly, the ferroelectric matrix in the hybrid nanosheets contains almost 100% ferroelectric phase. All the outstanding film properties guaranteed the success of ferroelectric organic non-volatile memories based on ferroelectricity-manipulated resistive switching. On the other hand, the PVDF LB films were further studied to develop spin valve devices with a sandwich structure of Co/PVDF/Fe3O4. Spin-dependent electron transport behaviors were systematically studied in these devices by varying PVDF film thickness from 7 to 30 nm. With increasing PVDF thickness, magnetoresistance (MR) response decreases likely subjecting to the change of spin transport from the tunneling to hopping transport. It is noteworthy that the MR effect was even observed at 300 K with a MR ratio exceeding 2.5%, which is achieved for the first time in such organic devices. The results indicate that the ferroelectric PVDF hybrid nanofilms are promising candidates for various electronics with outstanding performance.
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