I propose to construct a high resolution second harmonic generation (SHG) imaging system that will both surpass the resolution provided by current state-of-the-art magnetic imaging modalities and be nondestructive to samples. This type of imaging system does not rely on a synchrotron; this independence will remove the bottleneck in materials research created by many research groups requiring time on the limited resources of synchrotron sources. SHG imaging will be a key asset to many types of materials research, particularly the examination of sensitive materials such as thin films and organics--materials that often get damaged in traditional x-ray imaging. In addition, this technique allows for simultaneous imaging of ferroelectricity and magnetism at both interfaces and surfaces. When this quality is coupled with the improved resolution of the proposed SHG imaging system, it is clear that such a system is the perfect tool for studying the electric control of magnetism at interfaces.
Second harmonic generation (SHG) is a relatively new technique that allows the measurement of fields, electric and magnetic, primarily at interfaces and surfaces. It is a useful and important technique because it is a contactless and nondestructive approach to study—among others—injection, transport, trapping, and recombination processes in ultra-thin gate oxides at interfaces. When a laser light with frequency ω is incident upon the surface of a sample, light of twice the frequency (2 ω), in addition to the original light of frequency ω.
Recently, SHG has been developed into an imaging technique, allowing the imaging of not only ferroelectric and magnetic domains, but also some interesting biological systems. This imaging ability along with SHG’s nondestructive nature has thrust SHG into the forefront of magnetic measuring techniques, a field traditionally dominated by photoemission electron microscopy (PEEM) due to its 100 nm resolution. However, the x-rays required to excite the electrons and the vacuum environment in PEEM can be very damaging to some of the most exciting classes of materials, such as organics, thin films, and oxides. I propose a solution to this issue by improving the resolution of SHG. Current non-damaging SHG technologies already have 300 nm resolution, but the use of near field scanning could easily lower the resolution to less than 50 nm by transmitting the signal through a needle tip.
Check out the files below to learn more about some of my past research using SHG.
PHYSICS
Research Interests:
• Second harmonic generation studies in oxides, thin films and organics
• Electric control of magnetic structure
• Imaging of ferromagnetic and antiferromagnetic domains
• Exchange bias, coupling between antiferromagnets and ferromagnets
• Multifunctional materials with potential coupling with order parameters
• Piezoelectric force microscopy for the study of ferroelectric domains
• X-ray absorption spectroscopy and x-ray magnetic dichroism
• Modeling of expected dichroic contrast for different magnetic behaviors
• Internal photoemission to study spin relaxation in GaAs
