Nov 23, 2010
Universal assembly directs ultrahigh-density storage devices
L10 ordered alloys, such as FePt, CoPt and FePd alloys with high magnetocrystallic anisotropy, have attracted much attention thanks to potential applications in ultrahigh-density data storage. Great progress has been made in the controlled synthesis of nanocrystals, but the assembly or organization of nanoparticle arrays for device applications can be challenging. Now, scientists in China and Korea have developed a simple and general method for direct synthesis of ferromagnetic nanostructured arrays.
Researchers from KAIST and Pohang University of Science and Technology have studied inorganic nanopatterned arrays with a block copolymer template. Block copolymer can self-assemble ordered nanopatterns with a feature size of 5–50 nm. It is very suitable for ultrahigh-density nanodevice fabrication. The normal approach for patterning of inorganic nanostructures is usually based on selective etching. As an alternative, sol-gel chemistry combined with a block copolymer template demonstrates low-cost and large-scale production for nanodevice fabrication.
With the decreasing size of information storage devices, assembly of ultra high-density nanodot arrays will have promising applications. It is found that simple oxygen plasma can make a uniform porous polymer template (see left image). After a simple spin coating and thermal annealing process, a uniform ferromagnetic nanodot array (see right image) can be easily fabricated over a large area. It is also significant that a very high coercivity up to 10 kOe was obtained in a CoPt nanodot array.
This method can find attractive applications in the fabrication of ultrahigh-density storage media. Further experiments on other magnetic materials and optimal structures and properties are under way.
The researchers presented their results in the journal Nanotechnology.
About the author
The study was conducted at KAIST and Pohang University of Science and Technology. Dr Guodong Xia is currently exploring inorganic patterned nanostructures with polymer template for device fabrication and property improvement. Applications include various information storage and optoelectronics devices.