The study of antiferromagnetism did not gain popularity (due to its lack of a net magnetic field) until the discovery of exchange bias—the use of a thin antiferromagnetic film to pin the direction of a ferromagnet, resulting in a shifted hysteresis loop. This effect is used in modern memory devices despite contradictory theories on the origin of exchange bias; the mechanism behind the coupling between the antiferromagnetic and ferromagnetic layers is still under debate. There is some evidence that it is the behavior at the antiferromagnetic domain walls that is responsible. SHG is therefore a unique way to probe such systems because not only it allows access to the resolutions necessary to study these magnetic domain walls, but also allows access to the physics occurring at these interfaces.

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