A large area, monolayer of close-packed nano/microspheres can be used as a template or a mask to produce patterned nanostructures with interesting magnetic and optical properties. Spin-coating was used to create a densely packed monolayer of nano/microspheres of 400 nm, 1 μm, and 10 μm in diameter. To maximize the area of uniformly spin-coated monolayer of nano/microspheres, various parameters, such as spin speed, spin duration, and volume of the solution dispensed on the substrate, need to be adjusted. A multi-step spin-coating process was employed to increase the monolayer spread along with assisting in the evaporation process. After a systematic study of samples with Polystyrene and silica nano/microspheres made at various conditions, recipes for nano/microspheres of 400 nm, 1 μm, and 10 μm in diameter have been completed. Spin speed and spin duration turned out to be two critical tuning parameters to maximize the uniform deposition area. The chosen parameters yield 1 cm x 1 cm samples that are 90% covered with nano/microspheres. For 1 μm diameter microspheres, monolayer areas of about 140 μm x 100 μm were obtained. For 10 μm diameter microspheres, monolayer areas of about 4mm x 4mm were obtained. Silica nano/microspheres produced more uniform monolayers with less deformations than Polystyrene nano/microspheres. Permalloy or Samarium Cobalt were sputtered on the nano/microsphere templates. The magnetic properties of the nanocap layers were examined with an alternating gradient magnetometer and through the magneto-optical Kerr effect. Magnetic hysteresis loop measurements suggest that the magnetic switching is dependent on the size of the nano/microsphere. In addition, magnetic antidot nanostructures were obtained by removing nano/microspheres using Scotch tape after magnetic materials are sputtered.
|Commitee:||Kwon, Chuhee, Peterson, Michael|
|School:||California State University, Long Beach|
|Department:||Physics and Astronomy|
|School Location:||United States -- California|
|Source:||MAI 82/6(E), Masters Abstracts International|
|Subjects:||Applied physics, Materials science, Nanoscience, Electromagnetics|
|Keywords:||Hysteresis loops, Magnetism, Multi-step spin-coating, Nanospheres, Nanostructures, Self-assembly|
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