UC Berkeley

This dissertation details the study of electric and strain control of antiferromagnetism and ferromagnetism at room temperature using multiferroic BiFeO3 thin films. Piezoelectric force microscopy and photoemission electron micrscopy techniques were used to correlate ferroelectric and antiferromagnetic domains. An angledependent dichroism intensity formula was established and applied to determine magnetic behavior. The effects of thickness and orientation on ferroelectric and magnetic properties in BiFeO3 films were studied. These results were used in the making of a magnetoelectric-ferromagnet heterostructure in which electrically assisted exchange bias was observed. This toolbox of control parameters gives a very strong benefit for the making of new and improved devices, particularly in the computing industry where the traditional magnetic field controlled devices are reaching their limits.