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Magnetic Nanoparticle Arrays Self-Assembled on Perpendicular Magnetic Recording Media.

Mohtasebzadeh AR, Ye L, Crawford TM - Int J Mol Sci (2015)

Bottom Line: This increase suggests magnetic nanoparticle interactions evolve from nanoparticle-nanoparticle interactions to cluster-cluster interactions as opposed to feature-feature interactions.We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media.If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials.

View Article: PubMed Central - PubMed

Affiliation: Smart State Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA. ramoh87@gmail.com.

ABSTRACT
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle-nanoparticle interactions to cluster-cluster interactions as opposed to feature-feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials.

No MeSH data available.


Related in: MedlinePlus

Vertical line profiles taken from AFM scans as in Figure 3: (A) 120 min; (B) 60 min; (C) 30 min; (D) 15 min; and (E) 5 min. The full scales of the feature height axis are 80 nm for all five profiles, showing the increase in height as coating time increases.
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ijms-16-19769-f004: Vertical line profiles taken from AFM scans as in Figure 3: (A) 120 min; (B) 60 min; (C) 30 min; (D) 15 min; and (E) 5 min. The full scales of the feature height axis are 80 nm for all five profiles, showing the increase in height as coating time increases.

Mentions: To obtain average height, vertical image line profiles (Figure 4 shows example vertical line profiles obtained from the AFM images for each coating time) were extracted from the AFM images from both assembled features and empty spaces between features. The average of empty space profiles was then subtracted from the pattern profiles to obtain feature height. Note that there are non-assembled nanoparticles in the empty space regions, and these are included in the average background because similar nanoparticles are likely present in all regions. Figure 5 shows average height as a function of coating time, with height changing from ~13 nm (about 1 nanoparticle) to ~22 nm (2 nanoparticles thick) at 15–30 min, and finally to 36 nm (3 nanoparticles thick). Note these are average values, and Figure 4 shows substantial variation in height along a feature, which is reflected in the error bars in the average height plotted in Figure 5.


Magnetic Nanoparticle Arrays Self-Assembled on Perpendicular Magnetic Recording Media.

Mohtasebzadeh AR, Ye L, Crawford TM - Int J Mol Sci (2015)

Vertical line profiles taken from AFM scans as in Figure 3: (A) 120 min; (B) 60 min; (C) 30 min; (D) 15 min; and (E) 5 min. The full scales of the feature height axis are 80 nm for all five profiles, showing the increase in height as coating time increases.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581324&req=5

ijms-16-19769-f004: Vertical line profiles taken from AFM scans as in Figure 3: (A) 120 min; (B) 60 min; (C) 30 min; (D) 15 min; and (E) 5 min. The full scales of the feature height axis are 80 nm for all five profiles, showing the increase in height as coating time increases.
Mentions: To obtain average height, vertical image line profiles (Figure 4 shows example vertical line profiles obtained from the AFM images for each coating time) were extracted from the AFM images from both assembled features and empty spaces between features. The average of empty space profiles was then subtracted from the pattern profiles to obtain feature height. Note that there are non-assembled nanoparticles in the empty space regions, and these are included in the average background because similar nanoparticles are likely present in all regions. Figure 5 shows average height as a function of coating time, with height changing from ~13 nm (about 1 nanoparticle) to ~22 nm (2 nanoparticles thick) at 15–30 min, and finally to 36 nm (3 nanoparticles thick). Note these are average values, and Figure 4 shows substantial variation in height along a feature, which is reflected in the error bars in the average height plotted in Figure 5.

Bottom Line: This increase suggests magnetic nanoparticle interactions evolve from nanoparticle-nanoparticle interactions to cluster-cluster interactions as opposed to feature-feature interactions.We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media.If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials.

View Article: PubMed Central - PubMed

Affiliation: Smart State Center for Experimental Nanoscale Physics, Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208, USA. ramoh87@gmail.com.

ABSTRACT
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle-nanoparticle interactions to cluster-cluster interactions as opposed to feature-feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials.

No MeSH data available.


Related in: MedlinePlus