Tunable Magnetic Properties of Nanoparticle Two-Dimensional Assemblies Addressed by Mixed Self-Assembled Monolayers

Abstract

Assemblies of magnetic nanoparticles (NPs) are intensively studied due to their high potential applications in spintronic, magnetic and magneto-electronic. The fine control over NP density, interdistance, and spatial arrangement onto substrates is of key importance to govern the magnetic properties through dipolar interactions. In this study, magnetic iron oxide NPs have been assembled on surfaces patterned with self-assembled monolayers (SAMs) of mixed organic molecules. The modification of the molar ratio between coadsorbed 11-mercaptoundecanoic acid (MUA) and mercaptododecane (MDD) on gold substrates is shown to control the size of NPs domains and thus to modulate the characteristic magnetic properties of the assemblies. Moreover, NPs can be used to indirectly probe the structure of SAMs in domains at the nanometer scale.

Assembling of Magnetic Iron Oxide Nanoparticles Controlled by Self- Assembled Monolayers of Functional Coordinating or Chelating Trialkoxysilanes

“…After immersion in the NPs suspension, the SAM-THY is featured by a higher roughness (2.2 ± 0.1 nm) than the corresponding SAMs before immersion (0.5 ± 0.1 nm). These results are very similar to those obtained from SAMs prepared on gold substrates [10,11]. It appears that the higher roughness of gold substrates compared with silicon wafer does not influence the assembling of NPs.…”

“…Finally, no deposition of NPs was observed with non-interacting methyl head groups showing the importance of the former coordinating or chelating functional groups with the NPs. Mixed SAMs which display carboxylic and methylene groups with different molar ratios were accurate to pattern the substrate and thus to obtain patterned deposition of NPs [11][12][13]. Large assemblies of tight packed NPs or cluster of few NPs were formed selectively.…”

Exploring Exchange Bias Coupling in Fe3−δO4@CoO Core–Shell Nanoparticle 2D Assemblies

“…In contrast, the powder sample does not exhibit any jump. Fast magnetic reversal usually results from strong collective behavior between nanoparticles when increasing nanoparticle density . Therefore, we expect SAM‐2H to contain a large amount of 2D clusters with critical size which enhance the collective behavior of nanoparticles and predominates over exchange bias coupling.…”

Investigation of the deposition and thermal behavior of striped phases of unsymmetric disulfide self-assembled monolayers on Au(111): The case of 11-hydroxyundecyl decyl disulfide

“…However, the mole fraction of the components in the SAM may deviate from their mole fractions in the growth solution and phase separation may take place in the SAM depending on the concentrations of the precursor thiols in the solution and their chemical/structural degree of difference. [27][28][29][30][31][32][33][34][35][36] The latter method, on the other hand, suffers from the low solubility of disulfides and controlled variation of composition is not possible due to 1:1 ratio of R and R ′ groups. Nevertheless, large deviations from 1:1 ratio in the unsymmetric disulfide SAM were observed due to chemical/structural difference of R and R ′ groups.…”