title: Tuning Electron-Conduction and Spin Transport in Magnetic Iron Oxide Nanoparticle Assemblies via Tetrathiafulvalene-Fused Ligands.
abstract: We report a strategy to coat Fe3O4 nanoparticles (NPs) with tetrathiafulvalene-fused carboxylic ligands (TTF-COO-) 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's 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.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Zhong-Peng
authors.initials: ZP
authors.lastname: Lv
authors.affiliation: National Laboratory of Solid State Microstructures, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Zhong-Zhi
authors.initials: ZZ
authors.lastname: Luan
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Hai-Ying
authors.initials: HY
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Cheng-Hui
authors.initials: CH
authors.lastname: Li
authors.affiliation: National Laboratory of Solid State Microstructures, Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, P. R. China.
authors.forename: Jing-Lin
authors.initials: JL
authors.lastname: Zuo
authors.affiliation: Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States.
authors.forename: Shouheng
authors.initials: S
authors.lastname: Sun
keywords: Fe3O4 nanoparticles; TTF; electron-conduction; magnetoresistance; spin transport