Enhancing magnetoresistance in tetrathiafulvalene carboxylate modified iron oxide nanoparticle assemblies

Abstract

We report a facile approach to stabilize Fe3O4 nanoparticles (NPs) by using tetrathiafulvalene carboxylate (TTF-COO(-)) and to control electron transport with an enhanced magnetoresistance (MR) effect in TTF-COO-Fe3O4 NP assemblies. This TTF-COO-coating is advantageous over other conventional organic coatings, making it possible to develop stable Fe3O4 NP arrays for sensitive spintronics applications.

Pseudo Spin Valve Behavior in Colloidally Prepared Nanoparticle Films

“…Advances in colloidal nanosynthesis and characterization have largely shifted research from milled and biphasic solid-state materials to nanoparticle solids. These materials have led to increasing magnetoresistance ratios (Δ R / R max ) and an emerging understanding of how particle composition, − size, shape, and surface chemistry − modulate the tunneling magnetoresistance (TMR) that arises from intrinsic tunnel barriers between individual particles.…”

A Size Threshold for Enhanced Magnetoresistance in Colloidally Prepared CoFe2O4 Nanoparticle Solids

“…It should be noted that by this definition a perfect magnetoresistor will have Δ R / R = 100% instead of approaching infinity, as in definitions that divide by the lower value of the resistance (Figure S1). This empirical evidence suggests that nanostructuring is capable of transforming granular MR from a curiosity into a viable technology; however, from a synthetic chemistry perspective, only the barest surface of the materials parameter space has been explored. − …”

“…Ligand exchange of the native long-chain ligands to the small inorganic BF 4 – ion was performed according to a literature procedure in order to improve the conductivity of the final nanoparticle pellets. Although significant work has been done to improve conductivity and even control spin-transport through ligand design, ,, in this work we focus on high-temperature properties, and simply decreasing interparticle distance was sufficient to achieve viable conductivity. The removal of the hydrophobic ligands was evident from the ability to disperse ligand-exchanged nanoparticles in polar solvents such as dimethylformamide.…”

Synthesis of Electro-active Compounds Suitable for Adsorption on Metal Surfaces

“…Functionalized Fe 3 O 4 nanoparticles are formed using the monoacids 132-135 78 and the diacid 136 (Scheme 34). 79 The TTF-dicarboxylate 137 has been used as a molecular conductor to cross-link lead(II) sulfide nanocrystals. 80…”