Near-field scanning optical microscopy studies of oxygen movement in yttrium barium cuprate

In this dissertation, I determined the mechanism and experimental details associated with tunnel current induced hot electron migration of oxygen in the high temperature superconductor yttrium barium cuprate (YBCO). I developed a novel technique utilizing near-field scanning optical microscopy (NSOM) to induce electromigration on the nanometric scale. NSOM provides nanometric topography and subwavelength optical data simultaneously allowing for studies of electromigration on the nanometric scale using reflectance data. I determined hot electrons are the mechanism of oxygen movement in YBCO. I studied the dosage (current x time) and electron energy dependence of oxygen motion in YBCO. Spectroscopy of the voltage effect fits with the band structure, and show that minimum electron energy is necessary for an oxygen atom to be excited and thus move in the lattice. In addition, I performed structural, reflectance correlation measurements on the related compound strontium titanate (STO). I determined that scattering is important in modeling losses in the microwave for STO.