Optical properties of magnetic nanostructures
Magnetic nanostructures where all three dimensions are less than 100 nm are at the leading edge of research in data storage, spintronics and biomedical applications. The optical response of magnetic materials through the Kerr and Faraday effects has long been used to characterize magnetic thin films. Typically the Kerr effect is preferred whereby upon reflection the plane of polarization of a linearly polarized incident beam is rotated and reflection from an infinite (compared with the wavelength of the incident laser) thin film surface is well known.
Recently a number of intriguing effects have been discovered when, instead of a planar surface, light is incident on a nanoscale patterned surface. Here, the magnetic structures are typically much smaller (<100 nm) than the wavelength of the light (~ 500 nm). The observed effects include changes in both the sign and magnitude of the Kerr rotation. This suggests some interesting questions which require further investigation in order to understand the physical origin of the observations and the potential uses. As a minimum understanding the interaction of light with patterned magnetic surfaces is a key challenge if optical techniques are to be used to characterize novel recording devices such as bit patterned media (BPM).
This project involves studying the magnetic nanostructure-light interaction using and developing enhanced optical instrumentation. We have recently completed a new and unique instrument to give the capability necessary to study the small magnetic structures at different wavelengths and applied magnetic fields.The research work will focus on:
- Creating magnetic nanostructures using e-beam lithography
-Depositing novel multilayer magnetic thin films with perpendicular magnetic anisotropy based on Co/Pd and Co/Ni
-Determining basic magnetic properties
-Use multi-wavelength Kerr rotation magnetometry to understand the rich size -separation/depth/wavelength phase diagram
-Developing the Kerr instrumentation and measurement techniques
Having created thin films, the student will then pattern them into nanostructures ready for optical characterization which will allow the underlying physics of magnetic nanostructures and light to be studied.
The project will provide many opportunities to interact with other PhD students and postdocs within the group and to use a range of additional techniques to develop the fullest possible understanding of these magnetic thin films.