Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide
by
Oktay Yildirim 1,2, Tian Gang 3, Sachin Kinge 3,4, David N. Reinhoudt 1,4, Dave H. A. Blank 2, 
Wilfred G. Van der Wiel 3,*, Guus Rijnders 2,* and Jurriaan Huskens 1,*
Wilfred G. Van der Wiel 3,*, Guus Rijnders 2,* and Jurriaan Huskens 1,*
1
Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
2
Inorganic Materials Science, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
3
NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
4
Supramolecular Chemistry & Technology, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands
*
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2010, 11(3), 1162-1179; https://doi.org/10.3390/iijms11031162
Received: 16 November 2009 / Accepted: 3 March 2010 / Published: 19 March 2010
(This article belongs to the Special Issue Molecular Self-Assembly)
FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs onto the surface. The Al2O3 substrates were functionalized with aminobutylphosphonic acid (ABP) or phosphonoundecanoic acid (PNDA) SAMs or with poly(ethyleneimine) (PEI) as a reference. FePt NPs assembled on all of these monolayers, but much less on unmodified Al2O3, which shows that ligand exchange at the NPs is the most likely mechanism of attachment. Proper modification of the Al2O3 surface and controlling the immersion time of the modified Al2O3 substrates into the FePt NP solution resulted in FePt NPs assembly with controlled NP density. Alumina substrates were patterned by microcontact printing using aminobutylphosphonic acid as the ink, allowing local NP assembly. Thermal annealing under reducing conditions (96%N2/4%H2) led to a phase change of the FePt NPs from the disordered FCC phase to the ordered FCT phase. This resulted in ferromagnetic behavior at room temperature. Such a process can potentially be applied in the fabrication of spintronic devices.
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Keywords:
SAM; Al2O3; FePt; ferromagnetic; nanoparticle
This is an open access article distributed under the Creative Commons Attribution License
MDPI and ACS Style
Yildirim, O.; Gang, T.; Kinge, S.; Reinhoudt, D.N.; Blank, D.H.A.; Van der Wiel, W.G.; Rijnders, G.; Huskens, J. Monolayer-directed Assembly and Magnetic Properties of FePt Nanoparticles on Patterned Aluminum Oxide. Int. J. Mol. Sci. 2010, 11, 1162-1179.
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