Tuning Electron-Conduction and Spin Transport in Magnetic Iron Oxide Nanoparticle Assemblies via Tetrathiafulvalene-Fused Ligands

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• 作者：Zhong-Peng Lv ; Zhong-Zhi Luan ; Hai-Ying Wang ; Sheng Liu ; Cheng-Hui Li ; Di Wu ; Jing-Lin Zuo ; Shouheng Sun
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：December 22, 2015
• 年：2015
• 卷：9
• 期：12
• 页码：12205-12213
• 全文大小：542K
• ISSN：1936-086X

文摘

We report a strategy to coat Fe₃O₄ nanoparticles (NPs) with tetrathiafulvalene-fused carboxylic ligands (TTF-COO鈭? and to control electron conduction and magnetoresistance (MR) within the NP assemblies. The TTF-COO-Fe₃O₄ NPs were prepared by replacing oleylamine (OA) from OA-coated 5.7 nm Fe₃O₄ NPs. In the TTF-COO-Fe₃O₄ NPs, the ligand binding density was controlled by the ligand size, and spin polarization on the Fe₃O₄ NPs was greatly improved. As a result, the interparticle spacing within the TTF-COO-Fe₃O₄ NP assemblies are readily controlled by the geometric length of TTF-based ligand. The shorter the distance and the better the conjugation between the TTF鈥檚 HOMO and LUMO, the higher the conductivity and MR of the assembly. The TTF-coating further stabilized the Fe₃O₄ NPs against deep oxidation and allowed I₂-doping to increase electron conduction, making it possible to measure MR of the NP assembly at low temperature (<100 K). The TTF-COO-coating provides a viable way for producing stable magnetic Fe₃O₄ NP assemblies with controlled electron transport and MR for spintronics applications.